Is the concept of “spatial aspect” attested in any natural language?

I don't know of any languages where spatial marking is thoroughly compulsory in the same way aspect often is, however I do know of some potentially interesting cases of spatial marking. A lot of Papuan languages have grammaticalised systems for showing directionality and location. They are usually described as being relative to the speaker, but in at least some cases I have found them described as being relative to either the speaker or the village, or some other not wholly speaker-focussed system. The Nimboran languages in particular have highly complex systems e.g. Wilden(1976) describes Kemtuk as having the following system: https://i.imgur.com/cYKT8xS.png, but says that it is optional.  Anceaux (1965) describes 16 different spatial categories in Nimboran proper, but in a rather unhelpful manner. He notes that the unmarked position category, when the speaker is involved has a specific meaning of "near the speaker", but that it is also always used when the speakers position is indefinite or irrelevant, such as in stories or general statements. In at least some languages I have looked at, these markers were compulsory with motion verbs.

A somewhat different system involving location relative to other events is described by Huisman (1973) who reports that Angaataha has a class of medial verbs which are inflected for whether they occur in the same place or in a different place as the following conjunct.

As far as I can tell, none of this completely satisfies your request, but it shows that at least some things are definitely attested, and distinguish other, or more fine categories than what you've found yourself.


Is Basic English a well-defined constructed language?

The website describing Ogden's Basic English is here.
Wiktionary has the 850 word list here.

I would argue that Basic English is a (rather) well defined invented language.  Wikipedia lists it as a controlled natural language, which simply means that it is a natural language whose natural form and evolution have been suspended and its new form and evolution have been created by someone. In this case, Charles Ogden.

Classical Latin I have seen argued is a similar beast: a natural language that has some constructed or artificial tendencies, just not a single author.

The controlled language is, I would argue, the "fourth axial point of the Gnoli Triangle" --- the point where the art, science/engineering & practicality of invented languages become cotangent with the world of natural languages.

Basic English and its relatives might thus be seen as "conlang-natlang creoles". Where the creolisation process happens between two types of language rather than between two specific languages.

As for existing on its own, I think that is a rather different matter. If we were to replace the grammar with some kind of fundamental rule list and replace the English lexicon with unique, perhaps even levelled-Germanic words, we'd basically end up reinventing Esperanto.  Or Folksprak.  As such, yes, it could "exist on its own".

But Basic English is quite different among auxlangs, in that its essential function is that of a "bridge language".  It is designed to bring people who have no English at all across the gap and to a place where they can immerse themselves in the broader Anglophone world. Basic English is thus, in this key regard, self limiting in scope and usefulness.  It's great so long as the learner has extremely limited access to English speakers or English media.

As soon as that learner discovers the Internet or Anglophone aural culture (radio, television, movies) or English literature (broadly defined as anything written), they are going to discover the limitations imposed by Basic English. They'll have to leave it behind. In that sense, Basic English can't really have its own existence.

To build on your example: a Basic English speaker would simply have to step off the bridge and begin learning the "extended" lexicon of ordinary English!


How to choose a writing system for a conlang?

The answer mostly depends on your grammar and phonotactics:

Alphabets

Examples: Latin, Ogham, Mongolian. Alphabets are a pretty reasonable writing system for most spoken languages. I think there's a good reason why the majority of languages with standard written forms use some sort of alphabet. That said, they seem to take a long time to develop, so alphabets are unlikely for concultures that recently discovered writing.

Abjads

Examples: Arabic, Hebrew, Tifinagh. Abjads are good for languages with few vowels and very few minimal pairs distinguished by vowels. It's especially good in languages with triconsonental roots or other forms that undergo dramatic vowel shift as part of regular grammatical processes to improve coherence across grammatical forms.

Abugidas

Examples: Devanagari, Ge'ez (Ethiopic), Canadian Aboriginal Syllabics. Abugdias are pretty good for languages with relatively simple syllable structure (ideally not more complex than (C)CV(C)). Based on the real world, it seems that they're best suited for languages with a high number of tones or phonations.

Syllabaries

Examples: Hiragana*, Vai, Cherokee. Syllabaries are really only appropriate in languages with relatively simple phonology, ideally not more than (C)V (or adopt a pseudo-syllabary like the kana with separate symbols for coda consonants). Otherwise the number of characters grows exponentially, or will not do a very good job representing all segments of the language, though this is not necessarily a dealbreaker (cf. Cherokee).

* Hiragana is not a true Syllabary because each kana actually represents a mora, not a syllable.

Logographies

Examples: Chinese, Cuneiform, Mayan. Logographs are best suited to isolating and analytic languages. The earliest writing systems seem to be logographies though, so cultures that only recently discovered writing are most likely to have logographies.


How do languages manage to make sense with a free word order?

It should be noted that in addition to relying heavily on one strategy, it's also possible to mix strategies is various different ways, relying on different strategies to back each other up. For example in Fore(Kainantu-Goroka(TNG), PNG), there is a hierarchy like this, where if each strategy fails, the one lower in the list can be relied on. I'm putting "case" in quotation marks, because the "ergative" case marker in Fore is not really a case-marker as much as it is an often optional and occasionally prohibited derivational marker:

Verbal agreement
Animacy
"Case"-marking
Word order

Point 2, "animacy" means that referents higher on the animacy hierarchy are interpreted as being more likely to be agents, as such the NPs in a sentence like aebá nanita: yaga: amiye he pig food 3sg:gave_to:3sg "he gave the pig food" can be freely reordered without a change in truth value, despite the fact that the verbal agreement is wholly inadequate to disambiguate the roles of the participants. Only in the few instances where the other strategies fail is word order a primary disambiguative device.

There are some languages where a primary disambiguation strategy is marking on the verb whether such a hierarchy a broken or not, called direct/inverse marking (this can disambiguate situations with two 3rd persons of equal animacy as well by considering e.g. topicality or obviation).


Are there conlangs using constructed sounds?

Click consonants are rare in natlangs, but rather popular in conlangs, though despite this, given the existence of things like !Xóõ reality is stranger than most fiction in this specific regard. Language-game/conlang(?) turned actual spoken register Damin had several phonemes not seen in (other?) natural languages, such as an ingressive glotally interrupted unvoiced lateral fricative /ɬ↓ʔ/, an egressively released bilabial click /ʘ↑/ and stuttered bilabial trill /ʙ\ʙ/.

Searching for the various hypothetical combinations as well as ext-IPA sounds on google turns up a fair few instances of conlangs using sounds such as percussives, implosive fricatives, velopharyngeal and nareal fricatives, etc.

Outside of these humanly-possible, but non-attested outside of disordered speech phonemes, some languages made up for non-humans include sounds that are impossible for humans to make, such as this one spoken by a race of giants, including a special type of whistle-like sounds, or this one made for creatures with bird-like anatomy, differentiating between 4 different types of contraction of muscles in the throat overlaid with 5 different pitch contours.


Designing a vocabulary for geographical features

The first thing is: Design not only one word for each geographical feature, use several of them. To give some examples from a natural language (German in this case): A mountain may have a name in -berg (which is frequent in the mittelgebirge) but also -spitze, -horn, -kopf, or -kuppe. Some beacon mountains have names of their own without an element meaning "mountain" (e.g., Brocken, Großer Belchen, Kahler Asten, or Eiger). Similarly, cities are not just -stadt "city", but there are also cities in Germany with names in -burg, -berg, -heim, -reut, -furt, or -hafen.

The second thing is: Hydronyms are special. The names of larger rivers often reflect an older substrate and are not taken from the current language of the place and don't have any transparent meaning. Examples are Potomac, Arkansas, Mississippi, Missouri in the USA or Thames, Rhine, Rhône, and more in Europe.

With this in mind, the names on the map should show some interesting variation.


Which IPA phones can be made and understood underwater?

From reading the answers to the Worldbuilding SE you reference, I would draw the following conclusions:

anything unvoiced goes out of the window. So no /f/, /p/, /k/, /t/, /s/ etc. They are pretty useless, as they are predominantly in the higher frequency ranges (especially the fricatives) or very short and without much energy (which would be provided by the glottis). And higher frequency sounds travel less well in water.
consonants in general are either short (plosives) or prefer higher frequency bands (fricatives), so apart from /r/ and /l/ (and possibly /v/, /z/) would not carry well underwater.
vowels seem best suited. And looking at the frequency characteristics, those with lower formants seem slightly preferable, so /u/ and /o/, and the back /a/: vowels produced at the back of the vocal tract. The fronted vowels (/i/, /e/, frontal /a/) would have a higher frequency component again.

So in summary I would think a vowel-based phoneme inventory might be best. This inventory could be supplemented by some approximants (/l/, /r/, /j/, and /w/). Which is weird, as consonants usually carry most information in natural language!

Compare:

Whch s wrd, s cnsnnts sll crr mst nfrmtn n ntrl lngg!
i i ei, a ooa uuay ay o ioaio i aua auae!


Designing realistic pragmatics, particularly with respect to answering questions

Consider the following:
"I can't answer that."
"I'd rather not say."
"I don't understand the question."
"It's not that simple."
"It depends."
All of these are examples of non-answers which, as far as I'm concerned, are not rude. So I see no problem with designing a language that just has a non-rude particle for any or all of those situations.


How do Belters code-switch English and Belter Creole?

Nick has talked about how there is no “slang” per se in Belter. Languages like French are spoken both on the street and in high society, so there are multiple registers. It’s an introductory language for many people.

Slang is often used to exclude; if you’re not “one of us” but you still
Speak the language, you still are on the outside because you can’t quite follow what’s being said.

A language like Quechua in South America (according to Nick) doesn’t develop slang because speaking it is already a marker for being low-status socially (vs Spanish speakers). Speaking Quechua already excludes those on the other end of the linguistic divide.

Belter is similar. Nobody but Belters speak it (maybe some inner intelligence officers do, the way UK troops would learn Irish during the troubles. Speaking Belter is a mark of low social status.

Nick has said that he would imagine belters “fluidly speaking belt Lish. One can code shift on the fly between the two languages quite easily. If there amongst a bunch a rock hopper’s, they’ll probably all speak pure LB. When they’re on the docks, when there are more inners around, probably shift more towards English.

Belters have to speak English to deal with the UN/MCRN tax
Collectors. When they get boarded by Mickie Marines, you BETTER speak English. When they deal with the any government office, it’ll be in English.

In Haiti, the majority of the population are monolingual Kreyol speakers. But the language of Education and government forms is French. That leads to some fucked-up outcomes. I imagine Belter would be treated like Creole languages usually are; something broken & degenerate, not a real language.

The correspondence courses Naomi took were almost certainly in English. Nobody is translating engineering textbooks into a “degenerate” language like a Creole, and nobody is teaching this classs in LB. Hinikirii Brown’s tablet on Anderson Station was in English, although he father spoke to her mostly in LB.

Miller is a perfect example of code shifting. Watch his hands throughout the seasons; for a “welwala”, he is the most hand-gesturing Belter on Ceres. When interviewing Gia (who has just had a client murdered in her room), he interviews her in LB to set her at ease. But when talking to the Governor’s agent about the water thieves, he speaks perfect English.

Prax is an educated Belter. You don’t do botany classes in LB. and when he wakes up on the refugee ship, he first asks for Mei in English. When he realizes the crewman he’s speaking to is a Belter, Prax switches to LB. Prax spends so much time speaking English, shifting back into LB is something that takes a moment.

So yeah, my feeling is the code shift mainly comes from “am I speaking to a Belter, or an Inner?” The inner/Belter dichotomy is cooked into LB down to the level of pronouns the way social hierarchy is cooked into Japanese.

“Beltalowda” is the plural pronoun for “Belters” with the connotation of both “all Belters” as well as “us Belters” ( becaus again, almost nobody outside Belters speaks LB). “Inyalowda” is both “all inners” [No distinction between Earther or Martian], and “You inners”.


Well, from what we can glean out of the given texts, I'd be looking for something more like "at your service" rather than "good day".

I know the movies aren't canon, but Jackson depicts the Dwarves as not really comprehending Bilbo when tries to "good morning" them. And Gandalf's retort is classic. That greeting might be a cultural artifact of the Shire.

I wouldn't place too much faith in the lists you link to. They're fan art, which is fine as far as it goes. Especially the third one: that's just horrible garbled English. I mean really: Baruk Khazâd! next to Haw aru tauu? - - - I should think it would be difficult to make a worse reconstruction of Khuzdul.


Why are compound words in Volapuk hard to parse while compound words in Esperanto are not?

Esperanto phonotactics was never as restrictive as Volapük's. Its prefixes (including prepositional prefixes) are mostly not CV but CCV or VC, and its stems often enough begin or end with consonant clusters. So morphological boundaries are often easy to tell.

Moreover Esperanto initially avoided stem endings for multisyllabic stems that might be ambiguous with suffixes. Hence banquet becomes bankedo, not banketo, for fear of ambiguity with bank-eto "little bank".

Esperanto initially did pursue agglutinativity aggressively, and I'm not sure that it was less enthusiastic about doing so than Volapük. But malsanulejo is indeed exceptional for Esperanto.


How many active Klingon speakers are there?

According to Wikipedia, about 20 or 30 fluent speakers

Another more interesting article, a bit more scholarly, mentions a wide variety of numbers per study.


Are Interslavic and Neoslavonic the same conlang?

Depends on how you look at it; the Interslavic page does say (as you have noticed) that:

  All three projects collaborated closely with each other from that time, and in 2011 Medžuslovjanski („Interslavic”) was chosen as a common name. Fruits of this cooperation were, among other things, a common dictionary, a common news portal and a common wiki.

-- History of Interslavic

Thus, historically speaking, they are two different projects (plus a third one) that have coalesced into one, and are now one project with some internal variation. The websites are continuations of their individual parent projects, as each team retained its independence from the new fused project.


What do double consonants specify in Esperanto?

There are two questions (with answers) on the Esperanto stackexchange dealing with this problem (and yes, it is perceived as a problem even among Esperanto speakers):

Double letters in Esperanto
Asking specifically about Finnlando

The conclusion is: The double letter should be pronounced differently from the single letter, and it should be a true double consonant (not just a long consonant). Finnlando becomes hard to pronounce by these rules, and Esperantists are in fact shifting to the word Suomio.


What are reasons to construct an auxlang, artlang, altlang, etc?

I cannot speak for any other language creator, but I have done so as part of "worldbuilding" - for an alien world to have alien languages adds verisimilitude, and even if the language isn't actually heavily used, knowing how the language works and having a partial vocabulary lets me insert words from that language where there is no exact translation in English, or where the English would be a long circumlocution. As an example, one language I worked up has a word that means, literally, "a change in lighting that reveals new detail", but whose use has been extended to the metaphorical equivalent - and in one discussion in the associated story, after one character explained something to another, the second thanked the first - "That was a very useful kurìshdàm; thank you."


Should languages spoken by two similar races have the same protolanguage, or can they be not related by protolanguage?

I guess this is up to you as the world builder.

Note that there is no known connection between language and race, all human beings no matter of of skin colour, hair, or other characteristics used to define "race" can learn any human language as their first language. Large language families like Afro-Asiatic, Austronesian, or Indogermanic cross the boundaries of continents and races.

So again, it is up to you, depending on the in-world history, geography, and your personal preferences (some conlang inventors like modelling diachronics, other prefer to invent unrelated languages).

Note also that there is a phenomenon called sprachbund: genetically unrelated languages develop common features due to close contact. There is a famous sprachbund on the Balkan, there is Standard Avarage European, there are the Pacific Northwest languages forming a sprachbund with some interesting and maybe insipiring common features.


How can syntactic ambiguity with pronouns be avoided?

Here are three options you might want to consider:

Noun classes assign each noun a class (well known examples include the gender systems of Indo-European languages, and also the more elaborate systems of Bantu languages). Having pronouns agree with the noun class of the nouns talked about greatly helps reduce ambiguity, though it would likely not help in your specific example with two male human participants.

Obviation is the system of having two distinct third person pronouns, one (the proximal) referring to the most salient (important, topical) referent and one (the obviative) to less salient ones. In your example, likely Adam would be the proximal, and James the obviative. There are nice examples on the relevant Wikipedia article.

A third option, which is to my knowledge only attested in signed languages is Indexing. This is basically the human language equivalent of variables in programming languages: a new variable, usually a location in the sign space, is assigned to every important referent, and referred to by pointing at the location or otherwise involving the location during signing of relevant words. I believe Lojban does something similar to this as well.


Solresol actually reverses the syllable order of a word to denote an opposite meaning, though this occurrence is inconsistent through the creator's published dictionary. For example, fala means good, but lafa means bad, and falaredo means accessible, but dorelafa means inaccessible.


How can I talk about weather without expletives?

There are also language with impersonal verb conjugation, and of course, nothing prevents a verb from being used only in the impersonal. Nahuatl has an impersonal voice, but because it's only used with verbs that normally have animate subjects, its weather verbs function much like Spanish's, ironically enough.

In my own conlang Mfalen, weather verbs function as descriptors, so one says the equivalent of "X is raining" (i.e. It's raining on/in X) the same way one says "X is cold" or "X is windy" (or indeed, "X is red").


What are some reasons that constructed languages would want to have ambiguity?

If naturalness (being like a natural language) is a design goal, then a conlang can embrace ambiguity with no shame.
Efficiency. Most ambiguous sentences are understood well enough in the context they are uttered in, clarified either by prior knowledge, non-linguistic communication (body language, pointing, etc), or through follow up questions from the listener. When most ambiguity is not actually a problem, it doesn't need to be explicitly countered. To require a language to be completely and always unambiguous would require much more specific and cumbersome sentences, violating the cooperative principle.
Wordplay. Puns, double entendres, and garden path sentences are unlikely to be possible or productive without substantial ambiguity.


Is Schleyer's first sketch of Volapük available as a reprint?

To my big surprise the relevant issue of Sionsharfe is now digitised and freely available from Digitale Bibliothek München. The first sketch of Volapük at this moment still named only Weltsprache or Allsprache, the word Volapük itself can be found a few month later, occurs in Nr. 35, Vol. IV (1879) Beilage as a supplement.

What a fascinating document!

Following issues of Sionsharfe also contain shorter or longer fragments of Volapük, unfortunately the digisat ends with Nr 48 (1880), there are four more years missing.


What are the defining traits of a Euro-centric conlang?

The term "Standard Average European" (SAE) pretty much covers it, and has been around since the 1930s. Haspelmath listed a number of typical "Euroversals" in a portion of the 2001 book Language Typology and Language Universals. These are listed in a more readable-to-laymen way in the wikipedia article on the subject. Haspelmath included as true Europeanisms (that is, features that are part of the SAE Sprachbund) only features that fit the following requirements:

Most of the "core" European languages possess it.
Nearby languages (Celtic, Turkic, etc.) lack it.
Eastern Indo-European languages (Armenian, Iranian, Indic languages, etc.) lack it -- this prevents us from merely calling it a feature of the Indo-European language family as a whole.
It is not found in the majority of the world's languages.

The Europeanisms identified by Haspelmath that fit this criteria include:

Definite and indefinite articles
Post-nominal relative clauses with resumptive relative pronouns
The (transitive) perfect formed with "have" plus a past participle
Experiencers coded as nominative subjects
Passive formed with a participle plus "to be"
A preference for anticausatives over causatives.
Dative external possession
Negation with negative pronouns and positive verb forms (e.g., "Nobody comes" instead of "Nobody won't come.")
Particle comparatives
Relative-clause based equative constructions (e.g., "tan Z como X", "so Z wie X", "as Z as X")
Subject person marking used strictly for agreement (i.e., the verb is inflected for the person/number of the subject but the subject cannot be dropped)
Different forms for reflexives vs. intensifiers

He also identified several other features that were common among this Sprachbund but were not as well-documented as the above, such as the verb fronting of polar interrogatives (i.e., turning "I have done it" into "Have I done it?" to make a yes/no question), an inflectional marker for the comparative, and several others -- these are also included in the linked articles.


Are there differences between the Belter Creole of the books and the show?

Yes they are totally different.
In the books
Maybe because Daniel Abraham and Ty Franck are not language experts, the Belter language in the books is very simple, and not really a con-lang. It does not exhibit a plausible grammar and etymological evolution. In short, it's just words from different languages pieced together.
You can find a good list of examples inside the fan wiki https://expanse.fandom.com/wiki/Belter_Creole_(Books), with also the real languages the Belter expression come
A couple examples that pop up often in the books:
Bist Bien: "Are you okay" from German bist and bien spanish
The usage of "dui" from Chinese to say "yes!" "correct!"
In the TV
In the series, maybe producers had a bigger budget and commissioned the creation of a real con-lang, even if it is seldom spoken.
The words you hear in the TV are not in the books, and instead sound very plausible from etymologycal analysis:
Beltalowda = from "belter", corrupted in "belta" and "lowda" people
And this is a good example, you see the consistensy in how the word component is used:
Inyalowda = from "inner" corrupted in "inya" and "lowda" again! = Inner people.
The spelling corrupt from Belter -> Belta and Inner -> Inya is plausible in a language evolution context in the future.
Another example:
Welwala = from "well-dweller", the person who live in a gravity well
And in the TV movie, Belter language is also speak in longer sentences with full grammar rules. When in books it's always just random foreign words in the same sentence, but mainly in English
I hope this help you solving your doubt. English is not my mother language, sorry if is not clear.


Are there languages with five conjugations? If not, how would one construct one?

If you have two features (number/person), it seems tricky to have five options (or any other odd number for that matter). However, there is an easy way: simply collapse singular and plural for one of the persons.

There is actually a real example in English (and several other languages): the pluralis majestatis ("Royal We"). Simply discard the first person singular and use the first person plural instead.

We are not sure what other languages use this, but we have definitely heard it in English and German. It would not be surprising to us if it occurred in other languages as well.

Sounds a bit odd, but would be an easy option.


Is the alien writing in "Arrival" really a language? Can we form custom sentences?

The short answer: no, the language from Arrival is not a full conlang.
The logographs were designed by artists and designers, and, while some components of the logograms were assigned meaning, they did not define enough of its rules for it to be possible to make new symbols with definite meanings.
They did hire linguist Jessica Coon to consult on the film, and she annotated printouts of the logograms so the set designers would know what to put in the background and on the whiteboards (If I remember correctly, they consulted physicists for similar work as well). They also had Stephen and Christopher Wolfram provide some analysis and design the computer program used to analyze and generate the logograms in the film.
However, in the end, the movie was not for linguists or conlangers, so they did not design it as a fully fledged conlang—given that it's supposed to be a mystery they don't quite solve in the film, I don't think that's necessarily a bad thing.
These articles might interest you if you want more information.

How Arrival's Designers Crafted a Mesmerizing Alien Alphabet
'Arrival' nails how humans might actually talk to aliens, a linguist says


What legal aspects should one consider when creating a constructed language?

If I'm about to create a new conlang, should I consider any existing patents?

No. It is conceivable that conlangs might be patentable under US law, but none so far have been.

  entirely copying someone else's writing system would certainly constitute a copyright infringement;

Probably not. Again, it might infringe a patent, but there are very few patents on writing systems. Copying a specific font or typeface would constitute copyright infringement, but not copying the writing system in abstract.

  Where should I start here?

I'd start by reviewing Sai's talk at LCC 6 on the legal status of conlangs, and the accompanying slides and legal memo.

You might also review the Language Creation Society's involvement in the Axanar case regarding whether or not Paramount "owns" Klingon.


Is num-det-n-adj-rel a reasonable order for a noun phrase?

Reasonable: sure!

We do this in English, fronting the number for emphasis or for poetry. There's no reason why you couldn't do this as a matter of ordinary in your language.

Five the orange balls that Johnny saw  flew through air and bounced to jackadaw.


Constructing a language based on existing languages from different families

There should be no problem in doing so -- just mix and match features from the various source languages. A precedent for this for example is English:

the syntax/grammar is mainly Germanic, including many function words
the vocabulary is mixed (Latin, Norse, Anglo-Saxon, Norman French, Indian, ...)

I would choose on language as the "base" (in the English case it's Old English/Anglo-Saxon), and then modify it by replacing/adding some of the vocabulary from the different languages. Also, some grammatical features (morphological endings etc) could be mixed up.

If you do it iteratively (ie revising the language multiple times, simulating contact between the current version and another influencing language), you can also take into account other types of changes, such as dropping endings which are harder to pronounce, or making higher frequent words shorter and less regular.

What you do exactly is up to you, but there shouldn't be any problem from a linguistic point of view.


What has the impact of Star Trek: Discovery been on the development of Klingon?

The language still has Okrand's guidance, and he trusts Robyn to do it correctly.
From IndieWire:

Before Stewart initially took the “Discovery” job, she did check in with Okrand himself to make sure he approved. “He said, ‘You know what? I’m really glad you’re doing this for two reasons: One is so I don’t have to do it.’ Because just for a movie, it’s a lot of work, and the series goes on,” Stewart said.
But Okrand then added that he knew “the language is in good hands.” Said Stewart, “It was a huge ego boost for me — his confidence that I’ll do it correctly."

And even though Robyn Steward has Okrand's approval, every change has to get his stamp of approval before officially being added to the language.
TrekMovie tells us:

As was noted in the video, Okrand isn’t working on Star Trek: Discovery, as the translating for the show is being handled by Klingon expert Robyn Stewart. However, Okrand is still the only person who can introduce new words into the Klingon language, which is maintained by the Klingon Language Institute. As he does at each annual conference of the KLI (called the qep’a’), Okrand introduced a number of new Klingon words in the summer of 2017. You can see the full list at KLI.org (words noted as “qep’a’ 24” were announced this year).

So to address each question:

Has Klingon changed significantly since it has started being used for Star Trek: Discovery?

Nope - the people working on it are hardcore Klingon speakers, doing their utmost to keep everything accurate.

Has the vocabulary grown significantly?

Yes, it's grown - you can see exactly which words were added recently in the above link.

Has there been novel grammar revealed?

As far as I am aware, and from what Google turns up, no. The grammar is still the same as it was - just words are being added.

To what extent is the language still developing under Marc Okrand's guidance to meet the demands of the script, and how much leeway does Robyn "Qov" Stewart have in coming up with Klingon translations for the script?

As mentioned in the above quote from TrekMovie, Okrand still has control over the language - while Steward has some wiggle room like any other translation to any other language, she has to work with the language, only adding words when absolutely necessary.


Does Volapük contain any elements (order, participle, etc) not present in its European source languages?

The Volapük panoply of mood suffixes contains distinctions that were familiar to its audience through classicising education, but I think it fair to say they weren't in the immediate source languages: the optative, jussive, and potential moods as suffixes don't correspond to what German or English or French does morphologically; nor does giving a suffix to the apodosis of conditionals (if... then). In fact, while the optative is Ancient Greek and the jussive is Sanskrit, the potential in Europe is limited to Finnish, and the apodosis suffix seems to be completely made of whole cloth.

I'll add that, as with Esperanto, a lot of the compounding was schematic and not inspired by natural languages; the notorious example of lu- "derogatory prefix" is probably the most obvious (bien 'bee' > lubien 'wasp'; vat 'water' > luvat 'urine').


Which types of conlangs are the most popular to construct?

My experiences are largely the same as those of Adarain, though I have access to a data-set that perhaps better shows the predominance of artlangs, as I moderate a moderately sized discord server in which users can request roles that show what kind of languages they make and at the same time get a fancy-coloured name. Many users have more than one roles and the roles are not mutually exclusive either. The first number is the amount of people who have the role, the second number is the amount of people who have it as their primary colour:

A posteriori: 24, 8
A priori: 73, 19
Artistic: 66, 43
Auxiliary: 11, 8
Engineered: 16, 16
Joke: 8, 4
Secret (for secret communication): 12, 4

These numbers clearly show the dominance of a priori artistic languages. Additionally, all but one of the people with auxiliary as their main colour are relative beginners, though this a rather small sample and it may come down to server culture as much as anything.


I'm constructing a language with some rather hard-to-produce symbols. Computer or paper?

Well, LaTeX is a great platform for writing anything, and you already seem to use it to some success. So I suggest using LaTeX and creating pdf out of it for distribution.
What helps in the long run is creating a font with all the special characters for your conlang. TeX and LaTeX come with a reasonably usable font creation program called METAFONT, but the so created fonts are only usable in the TeX universe—which may be sufficient for you. I have successfully created fonts with METAFONT, and our partner TeX - LaTeX Stack Exchange has a lot of people that are willing to help with METAFONT.


Words for numbers in a language with bijective numeration

Just have two different words, like "twelve" (T) and "dozen". Than the number 1T is one-dozen-and-twelve.


Lovecraft probably didn't think about grammar, and we certainly don't have enough material to reconstruct one. Could also be like Sindarin, where Tolkien wrote much, but never released any specification of the language. Quote from the threat you linked: "To my knowledge, we only have the transcription in the Latin alphabet" (comment from Sparksbet).


Ostensibly, the transcription we have of R'lyehian is supposed to be a crude attempt to represent utterly inhuman sounds with the Latin alphabet. Most of what I can find on R'leyhian claims that it attempts to be an un-Earthly language: it does not distinguish between parts of speech, for example. It seems likely to me that Lovecraft at least attempted to invent a fully a priori conlang here.

I've found a Quora answer claiming the language "has basic elements of Welsh and German glottals," but it's unclear what exactly that means and where they got that information from.


Maximizing the distinction between affirmative and negative sentences

To maximize, it seems like at least you'd want to associate negation with:

independent words
conjugation/declension
your loudest phonemes
distinct word order
distinct prosody

You could have a number of independent markers/words as mentioned above.
Turkish has verbs which always negate, and Turkish verbs usually end the thought: e.g., 'değil' for "is not [noun or adjective]"; 'yok' for 'there is not [something].' For negating verbs, it has an infix as part of the conjugation. Reflecting back your point about 'can't,' as a non-native speaker, I can miss this negative infix sometimes. This, even though it is higher on the sonority hierarchy (easier to hear) than the plosive T you point out in 'can't.' (It uses M and a variable vowel.)
So, if you wanted to change a conjugation to express "not," say, instead of a T or even an M, you could try using the loudest sounds in your set (usually wide-mouthed vowels?), ha ha.
You could change word order for negated sentences. We do that for questions. I have noticed. Have you noticed? [rhetorical ;) ]
Also, you could reserve a certain, unusual tone, pitch, stress pattern, etc., for negating, like how it's pretty easy to hear the lilt we put at the end of a question? Not that this is exclusive of the other options, but imagine to say, "You can't have a muffin," you deepen your voice as much as you can and borderline-sing, "You can have a muffin." If people associated deep voice with negation like we associate that rising tone with questions, that'd be pretty hard to miss.


Is the Klingon alphabet inspired by Tibetan alphabet?

Considering this question is a rehash of another question on SX, I'm inclined to say it's chance resemblance — and not a very high one at that. It is very highly plausible that it was designed by a non-linguist at Paramount (if I understand correctly) at a time when there was no easy way of finding out about Tibetan even with the budding Internet of 1992 when the aforelinked article was published in the HolQeD journal of the KLI. The article specifically says:

  More recently we’ve been treated to a different alphabet, (often incorrectly attributed to Michael
  Okuda, scenic designer for Star Trek: The Next Generation™), one which corresponds to the phonemes of
  Klingon as described by Okrand in The Klingon Dicitionary. While the characters themselves are easily identifiable from background displays on Star Trek: The Next Generation™ (assuming one has access to video
  equipment and a reasonably large television screen), there has never been an “official” release describing
  the particular relationship between individual glyphs and specific sounds. As Okuda has indicated (HolQeD
  1:1, 11) all Klingon background displays are composed for appearance, not communication. And yet, an
  unofficial letter to a Klingon fan group from an unnamed source at Paramount resulted in the following
  alphabet: [...]


Do the ADVENT in XCOM 2 speak a real language?

In this article the dev team of XCOM 2 explain that they didn't have the time or resources to invent a full conlang, but instead made up gibberish that got across the sort of 'feeling' they wanted. In order to sound "darker and more ominous," they were deliberate in their choice of sounds for this gibberish, basing it on so-called "guttural languages" such as German and Dutch, and then they designed filters to make the voice actors sound more robotic.

  Steve helped shape the final sound by experimenting with the gibberish pronunciations that we came up with. In order to convey meaning to the player, we had to rely solely on the tone and delivery of the lines, with things like ‘Halt!’ Or ‘Enemy Spotted!’ coming across with more intensity than say a standard ‘I’m moving’ line. In the process I also tried to establish vocal patterns in each subset of lines to create some cohesion between the otherwise meaningless words the actors were reading.

A feat on the part of the sound designers and voice actors, to be sure, but not a proper conlang. Nothing stopping XCOM fans from expanding it into a full conlang, though!


Here are a few ways to deal with the problem of marking the vowels unambiguously:

Style 1 - normal Hebrew orthography

Considering the fact that there are no length distinctions or gemination, a transliteration into Hebrew would normally use exclusively these diacritics to represent the vowels:

a אָ *
e אֵ **
i אִי
o אוֹ
u אוּ

* add ה at the end of a word; and after letters other than א, add א in the middle of a word

** add ה at the end of a word

In addition, on נ (the only possibly coda in Toki Pona) the diacritic נְ would be used (except as last letter of word). Stress isn't normally marked even in vowelized Hebrew (apart from liturgy or texts for learners), and it's entirely unnecessary in Toki Pona, since there is no phonemic stress.

The advantage of this is that it follows ordinary conventions and is most easily intelligible to someone reading in Hebrew. The disadvantage is that implementing this kind of orthography is far from algorithmic and includes unnecessary information in the spelling.

Style 2 - minimalistic Hebrew orthography

Since Toki Pona is a minimalistic language, I think that a different transliteration convention would better suit it, to avoid redundancy in writing it. There is precedent for a more minimalistic transcription in the convention used for transliterating, e.g., Akkadian into Hebrew. Modifying it to suit Toki Pona's vowels, we get something like this:

a אָ
e אֵ
i אִ
o אֹ
u אֻ

Style 3 - Yiddish orthography

A third option, if you want to minimize use of diacritics, is to follow Yiddish spelling conventions. The only required diacritic is to distinguish between the two forms of א. The Yiddish convention of using וו instead of ו as a consonant can be safely ignored in Toki Pona. And actually, since there are no o/u minimal pairs in Toki Pona, you could get rid of all diacritics if you instead choose to use ו for both vowels, at the price of losing some information (style 4).

a אַ or א
e ע or ע
i אי
o אָ or ו
u ו

Sample differences

Roman x Hebrew x Minimal x Yiddish x 4-vowel
a     x אָ      x אָ       x אַ       x א
akesi x אָקֵסִי   x אָקֵסִ    x אַקעסי   x אקעסי
anpa  x אָנְפָה   x אָנפָ    x אַנפאַ    x אנפא
mije  x מִייֵה   x ֵמִי     x מייע    x מייע
mute  x מוּטֵה   x ֵמֻט     x מוטע    x מוטע
seli  x סֵלִי    x ִסֵל     x סעלי    x סעלי
toki  x טוֹקִי   x טֹקִ     x טאָקי    x טוקי
wawa  x וָאוָה   x וָוָ     x ואַואַ    x ואוא


Are there any grammatical aspects which do not have parallels in natural languages?

Well, y'know, ANADEW and all that, but...

As far as I know, there is no natural language with a grammaticalized antiperfect aspect--i.e., an aspect where the time of the action is after the reference point, rather than before.

Present Perfect: "He has come."
Past Perfect (pluperfect): "He had come."
Future Perfect: "He will have come."

In each case, the event occurs before the reference time defined by the tense. In the case of future perfect, this may or may not be before the present.

An antiperfect flips that around

Present Antiperfect: "He is going to come." / "He is about to come."
 (approximately)
Past Antiperfect: "He was going to come." / "He was about to come."
 (approximately)
Future Antiperfect: "He will be going to come." / "He will be about to come." (approximately)

The various English paraphrases all have some extraneous additional implications (e.g., "He was going to come" implies that he didn't actually, "about to" implies that the action is nearby) that are not inherent to the antiperfect aspect, if it were grammaticalized. The important thing is that the action occurs after the reference time, but not necessarily after the present. Thus, just like a future perfect action could have occurred in the past, a past antiperfect could occur in the future.


So, here are some of the implications of choosing secundative alignment. They aren't really strict implications so much as Stuff You Might Consider Thinking About™. I think the effects of choosing secundative alignment are pretty local overall and won't have cascading effects on your grammar. In my opinion, the thorniest issue here is dealing with valence-changing operations on verbs.

What do secundative languages tend to look like in the real world?
How does secundative alignment manifest itself in morphology or syntax?
Valence-changing operations
Relative Clauses

Real World Secundative Languages.
If you want your language to be naturalistic, I suggest taking a look at WALS to see what kinds of combinations of features are typologically uncommon. If you are not trying to make a naturalistic language, knowing what natural languages tend to do is a good way to spend your "weirdness budget" wisely.
This map marks the strategy used for the verb to give. This analysis could be misleading because it's possible for the verb give to use a different strategy from other verbs, but I think this feature is the best fit for what you're after of the available WALS features.
Looking at the map, my assessment of the broad areal trends is that Eurasia is dominated by the indirect object construction. The secondary object construction seems to be common in North America and in New Guinea.
The WALS Chapter for this feature provides some examples of the different types of constructions as well as a note about what other features commonly co-occur with secondary object marking, excerpt below:

...head-marking languages with verb indexing of two core arguments tend
to show the secondary-object pattern...

How does secundative alignment manifest itself?
Basically, there are four ways your language can manifest secundative alignment.

word order
presence of dedicated adpositions
case markers
verbal agreement

I think most of the real world secundative languages are secundative because the recipient in the verb to give or other similar verbs gets indexed in the verb the same way that a prototypical direct object would.
This can occur in a language with no case marking. So, I give you the book might be something like
book.sg  give.1sg-subj.2sg-obj

In this example, book bears no case marking but is clearly the theme.
The case marking strategy is covered in your example.
For word order, we can take an example from English.
I give you the book

you is the recipient, but occupies the position directly after the verb. In English you have a choice between using a preposition like to or for instead. If no such option existed, this would be a pristine example of syntactic secundativeness.
Note that the language can be partially secundative.
For instance, the following is possible.
you.sg.DAT book.sg.ACC give.1sg-subj.2sg-obj

In this example, the two non-agent arguments book and give receive indirect-object-style case marking, but the verb shows secundative alignment.
Valence changing operations
It is important to think about how the passive voice, if it exists, should behave.
Suppose we have a language with secundative alignment in its cases.
I.NOM you.OBJ book.INST give.PST
I gave you a book.

If you were to passivize the verb, which argument would be promoted to the agent? Would (101), (102), or neither be acceptable?
(101) you.NOM  give.PSV.PST
(102) book.NOM give.PSV.PST

Do you have an anti-applicative voice that deletes the recipient and promotes the theme to primary object? As far as I know, anti-applicative voices do not exist in the real world, but applicative voice does exist. It's possible to allow this promotion without an explicit voice for it.
I.NOM book.OBJ give.ANTIAPP.PST

This situation gets murkier if the language is both ergative and secundative.
I.ERG you.ABS book.INST give.PST
I gave the book.

In this case, the antipassive voice would delete the absolutive argument and promote the ergative argument.
I.ABS book.INST give.ANTIPSV.PST
I gave the book (to someone).

Some ergative languages mark instruments and agents the same way.
I.ERG book.ERG you.ABS give.PST

In this case, the antipassive voice could potentially target either argument.
I.ABS give.ANTIPSV.PST

or
book.ABS give.ANTIPSV.PST

Relative clauses
Deciding how relative clauses in secundative languages should work might present some subtle issues.
Languages frequently have a limit on what kinds of arguments can be targeted by relative clauses.
You may want to choose to make only the agent and the primary object extractable, but not secondary objects.


How did Tolkien model diachronic changes in his Elvish languages?

OK, here are some details on classical Quenya and classical Sindarin (based on Helmut W. Pesch, Das große Elbisch-Buch, Bastei-Lübbe 2009)

The phoneme inventory of Primitive Quendian was

p   t   k
pʰ  tʰ  kʰ
b   d   g
m   n   ŋ
    r,l
        ɣ
w     j
a, e, i, o, u, ai, oi, ui, au, eu, iu

An early addition to this repertoire were prenasalised consonants mb, nd, ŋg that developped differently in Quenya and Sindarin.

Sound shifts for Quenya

pʰ   tʰ   kʰ  -> f   θ   x  (later: θ -> s)
b-   d-   g-  -> v-  l-  Ø
-b-  -d-  -g- -> -mb- -nd- -ŋg-
mb-  nd-  ŋg- -> m-  n-  ŋ-   (later: ŋ- -> n-)

The loss of almost all b's, d's, and g's makes Quenya phonological similar to the Finnish language.

Quenya has some old compounds that preserve the pre-shifted state of a root, e.g., for dome > lome "night, darkness" there is an old compund tindome and a newer regular one Aldalome. This adds to the diachronical depth of the language.

Sound shifts for Sindarin

p    t    k   -> b   d   g
pʰ   tʰ   kʰ  -> v   ð   ɣ (later: ɣ -> Ø)
mb-  nd-  ŋg- -> b-  d-  g-
kʷ  -> p
w-  -> gw-

Sindarin also has a lot of lenitations (i.e., in certain contexts the initial consonsonant of a word is changed to some "softer" consonant) inspired by Welsh. The lenitations are different for original b d g and b d g that come from mb  nd  ŋg. Sindarin also has acquired an umlaut y.

EDIT 3: Evolution of initial sp-, st-, and sk-

Both in Sindarin and quenya, consonant clusters with an initial s were simplified in two steps: First, the stop became aspirated and the s was dropped

 sp st sk -> pʰ tʰ kʰ

and than the aspirated stops became voiceless fricatives

 pʰ tʰ kʰ -> f θ h

In Quenya, also the so-created θ's became s later, such that the net development of Quenya is

  st -> s

EDIT 1: Some more information gleened from the dictionary

Quenya Words beginning with h- derive from Primitive Quendian roots beginning in kʰ-. The initial consonant cluster stʰ was simplified via θ to s.

Some words beginning with  ç- like hyarmen "south; left side" come from roots beginning in kʰj.

Sindarin  has simplified some consonant clusters like kl- kr- via intermediate voiceless l and r but in classical Sindarin those l's and r's are the usual voiced ones (despite being retained in orthography as lh rh).

EDIT 2: The grammatical changes aren't explained in great detail. It seems that Tolkien applied some handwavium here when he states that Quenya was consciously changed for greater clarity. On the other hand, Sindarin has evolved naturally (in Tolkiens internal history) in the woodlands of Middle Earth where everything is interwoven with everything.


Good Real World Languages to Base Proto-Lang Vocabulary

One suggestion I'd give: use Proto-Indo-European lexicon for the words you want in your own proto-language, then use a word generator to create the actual roots of your language. That way you're not going to run into the problem of a having a word list that accidentally includes terms your proto-speakers would be unlikely to have.


A Hypothetical Mediterranean Language Inspired by Both Greek and Latin

The situation you describe, in which Classical Greece invades the Roman Republic, has two probable outcomes. (This is assuming a single language "merged into one" excludes the possibility of both languages coexisting. However, a language can also exert influence on another without supplanting it.)

If the Romans adopted (or were forced to adopt) their conquerors' language, which is what happened in other nations after Alexander the Great's conquests later in history, then the spoken language would become Greek. The influence of the Latin language in such a case would exist as a substrate, which could introduce Latin loan words and grammatical structures into Roman Greek.
If the Romans didn't choose (or weren't forced) to adopt Greek as their language and continued to speak Latin, then Latin would remain the spoken language, but would have Greek influence on vocabulary and grammar, as a superstrate or adstrate. As it is, Latin already has Greek influence on its vocabulary, with learned words like philosophia; but in the case of a Greek conquest, it would probably gain more mundane words as well.

A comparable case in history with regard to English could be the Norman invasion of England. Anglo-Norman and English were spoken alongside each other. Eventually, English was the only language spoken of the two in England, but not without considerable influence from Anglo-Norman. Looking at this case might give an idea of how a language could change followed by the invasion of another one.


The best possible approach to a writing system "from the middle" is probably a text spiralling outwards.

One famous artefact, the Phaistos Disk, shows a spiral layout of the text, but is is unknown whether it should be read inwards (most scholars prefer this) or outwards and the writing system is still undeciphered.

Your graphical samples suggest a symmetric progression of symbols to the right and left—I think this is unrealistic because lazyness and economy of writing will soon lead to the abandonment of one of the symmetric halves, leaving either right-to-left or -left-to-right writing.


Does Lojban completely remove semantic ambiguity?

Let's take an element of Lojban's grammar, and see if it's semantically ambiguous.
In lojban, tanru are basically two predicates in adposition. The first one semantically modifies the second one; and that's all.

Example:

{lo zdani gerku cu barda}: The house dog is big.
{lo gerku zdani cu barda}: The kennel is big.

Where {zdani} (roughly) means "home", {gerku} means "dog", and {barda} means "big (the rest is grammatical witchcraft, don't bother).

In the first example, {zdani gerku} is syntactically a tanru, and {zdani} modifies {gerku}. However, the tanru is primarily about {gerku}.
In the second one, it's the reverse. {gerku zdani} is also syntactically a tanru, but {gerku} modifies {zdani}; and the overall tanru is about {zadni}, not {gerku}.

However, it isn't possible to make assumptions about the overall meaning of a tanru. Though it's syntactically not ambiguous, it is semantically ambiguous.
I've chosen the english “house dog” and “kennel”, but it was just my intent, and english translates this way. Officially, it's not possible to infer the meaning from a tanru.

You can even read yourself in the last official reference grammar that “All tanru are ambiguous semantically.”

For a surer version:

{lo gerku poi ta'e zvati lo zdani cu barda}: The dog that uses to live at the house is big
{lo zdani poi zukte ke'a lo nu stuzi lo gerku cu barda}: The house that is aimed so that dogs could live in is big.

EDIT: added an explanation on how it's ambiguous, and the surer examples.


How typologically unusual is using postpositions in an otherwise head-initial language?

Such languages are uncommon but not unattested. However, they are more common than prepositional SOV languages and are present in a number of unrelated families around the world.

This WALS map shows us that in general, the order of object and verb and adposition and noun phrase is very highly correlated. In the map, postpositional VO languages are the group with the third highest number of total languages, but they are less than a tenth as common as the most frequent types.

 Postposition / OV    472
 Preposition  / VO    454
 Postposition / VO     41

There are some parts of the world such as West Africa where there are many SVO languages with postpositions. There seems to be a cluster of them around Côte d'Ivoire and Ghana. I think the languages in question are proven or suspected to be Niger-Congo languages. The westernmost group of these languages has both VO and OV languages as well as some intermediate types like SOVX languages and postpositional VO languages.

Another example of a postpositional VO language is Finnish. I think Proto-Uralic is generally reconstructed as having verb-final word order. However, many of the modern groups of Uralic languages have SVO word order.

There are a few cases of languages with verb-initial word orders with postpositions. One such example is Yagua. Yagua is an interesting case because the verbs are very highly inflected, but the nouns are not.


It happens with sign languages - often there are two "versions" of a sign language, the first one (less official, natural) is generally used by the community and has its own grammar, the second one (more official, heavily constructed) parallels grammar (syntax) of the corresponding spoken language.

E.g.there is the natural Polish Sign Language, and a rather artificial constructed Signed Polish, following closely the syntax of spoken Polish, so somewhat the opposite of the question, a natural language imposing its grammar over the conlang. But it could be said that the signing system (obviously) imposes its own "phonology" over the spoken language.


What is opposite of "burzum", "darkness", in Tolkien's Black Speech?

As @Darkgamma says, we don't know.  The closest we have would probably be ghâsh, which means fire, and one could probably guess that the characteristic of being fire-like would be something like ghâshum, but there is no empirical evidence for that, except that the suffix -um seems to mean -ness, as in burz- (meaning dark) + -um (meaning -ness), put together to form burzum.

That said, ghâshum would literally mean "the characteristic of being like fire," not literally "lightness."


Everything in this answer is taken from the website of the Láadan language (link to the page).  I am by no means an expert, but this is directly from the mouth of Laáadan's creator.  The following quote contains pertinent excerpts of the article, parts of which I have put in bold:

Another goal I had for Láadan was that it should be as easy as possible to figure out what a particular word or morpheme means just by looking at it...I wanted the language to work like a Tinkertoy® set works, so that people could take the pieces and fit them together easily to make larger forms. For example: the Láadan word for “bee” is “zhomid”; that word is made from “zho” — the Láadan word for “sound,” and “mid” — the Láadan word for “creature.” The meaning is transparent from the word’s parts.
First, however, I had to construct the most basic elements of the language — the words/ morphemes that are called “roots” and can’t be taken apart into smaller meaningful pieces. When linguists begin working with a language for which no grammar or dictionary is available, they ordinarily start with a set of roughly 100 very basic words made up of items like “eat” and “sleep” and “food.” I followed that practice, and began by constructing a core vocabulary of those basic words; when I had those done I began adding additional roots that I felt were needed. Sometimes I can explain to some extent how I chose a particular shape for one of those words; much of the time I can’t.
For example… I can explain that I chose “oódóo” for “bridge” because when pronounced its tune makes the shape of a humpback bridge. I can explain that I chose “rul” for “cat” because the purring of a cat sounds to me like “rulrulrulrul…” But the choice of “ana” for “food” and “ina” for “sleep” was arbitrary; I have no explanation for those choices other than that I tried to give them a shape that could easily be combined with other morphemes. For any constructed language that isn’t based on some existing language, the hardest part will always be putting together the inventory of roots.

An update to the Láadan dictionary shows that not all of the words were created by Suzette Haden Elgin (the creator of Láadan) but all that are not roots in and of themselves--roots which seem to have been created rather arbitrarily--can be figured out from these roots.  For example, in the dictionary I linked, the word for beaver is "eduthemid."  This contains the rood for animal, "mid," and some other root, I presume "eduth."  I do't know what this means, but it was constructed in this way so that someone who knew these roots but did not know the word could discern that it means beaver.
The original creator of Láadan made a couple of arbitrary roots that could then become a lexicon through a logical process of morphology, with help from multiple other people.


Good cultures to base a robotic language off of

Humans in such kind of situation devolop a Pidgin specifically for trade. It is arguably easy not only for humans but also for robots: no complicated ingredients in syntax nor morphology, and also usually a simple phonology.


What are the main limitations of Lojban?

Length

A few things. First, Lojban often needs longer sentences to express something than it does in, for example, English.

Vocabulary

Secondly, Lojban's vocabulary isn't that big, especially in the domain of sciences. Words would have to be calqued, adapted from English, French, etc. or completely re-invented.

Loaning and naming

Thirdly, the English language (and many natural languages) loans words directly (for example, champagne could be *shampain and buoy could be *boy or *boi) without changing spelling (a slight counterexample would be German, which often changes the letter c pronounced [k] to the letter k, like Kanada and Vokabular).

Lojban doesn't. .Romas. is Rome (Italy), .xavanas. is Havanas (Cuba) and .lidz. is Leeds (UK). This makes it confusing in some cases. How would Lojban adapt Turra Coo or people like Nelson Rolihlahla Mandela? The name should stay recognisable but pronounceable.

Rhetoric

Furthermore, many rhetorical devices such as these would be boring, simply boring. Shakespeare would be an ordinary novel writer, the Bible no longer so majestic and this sentence boring. Language would be unambiguous: literature boring. Language needs rhetoric, rhetoric needs language. Epizeuxis. Epizeuxis. Epizeuxis. Alliteration acts amazingly when all aposiopesis achieves is... Aposiopesis achieves... Aposiopesis... Rhetoric is not unlike magic. What would we have without rhetoric? We'd have a boring and a world. Rhetoric, her voice is beautiful, her heart full of peace and her prosopopoeia angel-like.

Well, to finish that rant, try to translate this to Lojban.

  A shocking affair occurred last night. Sir Edward Hopeless, as a guest at Lady Panmore’s ball, complained of feeling ill, took a highball, his hat, his coat, his departure, no notice of his friends, a taxi, a pistol from his pocket, and finally his life. Nice chap. Regrets and all that.


Nasal consonants are not nasal because you use any "nose muscles", but because the nasal passage is open and air is passing through it as well as the mouth. To my knowledge, the nasal passage does not have different degrees of being open or closed, so there wouldn't be any way to make a nasal consonant more nasal.

However, there are definitely some sounds that are less nasal than standard nasal stops. Prenasalized and poststopped consonants, where a nasal followed by a non-nasal stop is treated as a single consonant, exist and are phonemic in some languages. There are also denasal phones, in which the nasal passage is open and used as a resonant cavity but air does not flow out the nose (think of how someone sounds when they have a stuffy nose). While denasals are not phonemic in any natlang to my knowledge, they are sometimes allophonic or phonetically present in a language that is losing its nasals.


How to make good analogy in one's constructed language?

Let's look at a made-up example. Assume that we want to apply a sound change from /g/ to /d͡ʒ/ before /e/ and /i/ in Esperanto. Then, the conjugation of the Esperanto verb pagi "to pay" suddenly becomes irregular:

paĝi, pagas, paĝis, pagos, pagus (The infinitive and the past tense have a different consonant (ĝ) than the rest).

Analogy will force one consonant for all forms but we cannot predict which one. In this respect, analogy is quite irregular, and we can end up either with the original Esperanto paradigm, or with all forms shifted to the new consonant (paĝi, paĝas, paĝis, paĝos, paĝus).

Analogy affects usually inflected or agglutinative word forms, such as verbs and nouns, but it can also be applied to derivational morphology.

Another type of analogy tries to level out differences between conjugations or declensions. Assume, your language features two different conjugations. Than borrowing an ending (or prefix, or vowel change) from one conjugation to the other is also an analogy.


How would the grammar of a conlang develop as a creole from other languages?

I would think that it relates to the power structures behind the language communities, and to their relative size.

This can be kind of observed with English after the Norman invasion. The basic English grammar still remained Anglo-Saxon (as the majority of the population spoke it), and the main influence of Norman French (the powerful but small elite) was in the vocabulary. There are a few instances (eg putting some specific adjectives after the noun, as in president elect or times past) where French structures were adopted.

I would think that vocabulary is more a conscious choice, and Norman power made people adopt French words, but the grammatical structures being more sub-conscious meant that they were harder to change.

Another issue is how closely related the origin languages are. Obviously, while Norman French and Old English are different families, they both share the Indo-European ancestry, so are not that radically different. Compare that to, eg the Philippines, where there is a great language variety, and Asian/Polynesian languages clashed with Spanish/English in the colonial period. Here is one creole, Chavacano, which apparently has mostly Spanish vocabulary (so that it is classed as a Romance language), but their grammatical structures are generally similar to other Philippine languages (Wikipedia).

So it seems that power drives the vocabulary, but quantity of speakers determines the grammar.


How much of Tolkien's "black language" exists?

Am reading through LotR now, and have just finished H, Lost Tales, R, FG, etc. so the memories are still pretty fresh.

The Ring verse is the longest bit of Black Speech, followed by Grishnákh's bit of invective towards Ugluk. Other than that, there's only a couple individual words (like snaga, slave and ghash, fire) to be found.

Tolkien himself wrote as much in a letter (No. 144) to a reader of page-proofs (presumably of LotR): ...[Black Speech] only occurs in the Ring inscription, and a sentence uttered by the Orcs of Barad-Dur and in the word Nazgúl.

A related query on the Black Speech.


After all, there is a limited number of shapes that one can draw with reasonable effort. You can measure the effort for writing a character in a writing system by the number of strokes needed. For alphabets, there should be no more than 5 strokes, for a syllabary maybe 7 or 8.

But there are more shapes available than you may think: For a relatively recent (in terms of writing systems) invention, you can look at the Canadian Aboriginal Syllabics having a distinct look from other writing systems.

The different Indic writing systems are also a good source of inspiration: While sharing a common set of characters and common principles, the letter shapes are always different in the various Indic and Indic inspired (like Thai or Khmer) scripts.

And it is still possible to invent a new and distinct writing system from scratch: Tolkien's Tengwar shows clear external influences (from Indic scripts and from Francis Lodwick's Universal Alphabet) but is clearly distinguished from both sources of inspiration.


It would probably be a question of volume and frequency pattern. Loud sounds would travel further (and thus have more potential for echo). I would like to stress that I too have no cave to try this out, so there is a certain speculative aspect to this answer.

So, avoid vowels (obviously), and voiced sounds (prefer /p/, /t/, /k/, /f/, /s/ over /b/, /d/, /g/, /v/, /z/).

However, such a language would be pretty hard to use, so you'd need to compromise. Assuming low frequency sounds have less energy, the vowels /u/ and /o/ might be suitable, and perhaps the schwa.

Plosives (/p/, /b/, /t/) feature a burst as the air is released, which might also not work well, so you're probably better off using fricatives.

That leaves you with voiceless fricatives: /f/, /th/, /s/, /S/, /h/. Though voiced, nasals might also be suitable, as the mouth is closed during the articulation and thus it is possible to pronounce them without releasing too much acoustic energy.


What verbs should be irregular in a naturalistic conlang?

The first class of verbs that is often highly irregular are the auxiliary verbs. This does not only comprise to be and to have but also the modal auxiliaries (like must, can, shall, and will). They are used very frequently and tend to erode phonetically, and they are also prone to suppletion (showing a mixture of different stems from originally different words).

A quick check (for my native language German) seems to confirm your intuition that verbs of motion are more often irregular than average. They are also used quite frequently. In Romance languages, the basic verb for to go (e.g., French aller or Italian andare) is very irregular and mixing several different stems ((vulgar) Latin ambulare/allare, vadere, ire).

Some verbs are irregular because they rhyme with an irregular verb, e.g., German schreiben, schrieb, geschrieben "to write", borrowed from Latin scribere, became irregular because of rhyming verbs like bleiben "to stay".


What language uses the most amount of phonemes?

You're gonna have a hard time with "majority of the entire IPA". Non-pulmonic consonants are rare, and some consonants are hard to contrast (e.g. /β/ vs. /v/), while vowels are often highly allophonic. Natural languages tend to have fewer IPA places and distinction via aspiration, labialization, etc.

My best answer to your question would be Ithkuil (constructed, almost unspeakable language). It has 58 phonemes, with unusually many vowels (13). This allows it to have mostly single phonemes for morphemes. Ithkuil's Roman transliteration is a bit strange, as some phonemes use diacritics and others have digraphs, but it also has its own script (morpho-phonemic with alphabetic characters).


Are there any free online conlang creation tools?

There are some syntax "toys" online, eg http://www.zompist.com/gtg.html. This will help you write a (formal) grammar of your language, but you will need a good understanding of Generative Linguistics to use that.

Otherwise, what else do you need instead of pen and paper? Maybe a spreadsheet to enter vocabulary? There are so many choices to be made on so many levels that it is not really possible to automate much of it. It's not as if you would enter a few characteristics into a form, press a button, and out comes a conlang :)


Are there conlangs which compel their users to speak with honesty?

I don't think that languages, whether natural or constructed, have this power.

The fact is that there are numerous ways to be deceptive. You can straight out lie, you can speak as if there is uncertainty when really there is not, you can be deceptive through what you don't say, and you can be deceptive by saying true facts that are not actually strictly relevant, something called "paltering".

Like most linguists now, I think that the weak Sapir–Whorf hypothesis, that our language influences our thoughts and decisions, is surely true, but I am sceptical about the strong version, that language completely determines and limits our thought categories. Either way, I don't think it's really relevant to the aspect of human psychology which makes deception possible. Lying through omission or distraction is possible because our minds can generate multiple possible statements to make to others, each disclosing a different level of truth, but none of us are compelled to speak every thought that enters our minds.

Perhaps someone has invented an alien species with an alien psychology and an alien language to speak, and maybe in their universe their language does compel them to speak honestly. But what would it mean to prove such a thing, and how could anyone else present an argument to refute their claims? So for humans I say the answer is no, and for fictional creatures it's not a useful question for us to ask.


Is there a constructed language in existence that has graduated to "natural" status?

For varying definitions of "conlang", yes:

The very most obvious example is Esperanto with a well-documented native speaker community. It has received limited official recognition, the most interesting of which currently seems to be PR of China's El Popola Ĉinio magazine and China Radio International in Esperanto. There are many more.
A less obvious example would be Classical Sanskrit, which was, arguably, constructed by Pāṇini, and is a Scheduled Language of India with some fifty thousand people speaking it in 1991; it is furthermore an official language of the Indian state of Uttarakhand, and reportedly the language of the majority in a village called Mathoor. It is used across all levels of education across India.
A more controversial example would be Modern Hebrew, one of the few successfully revived language in modern times. The page on Wikipedia gives a solid overview of the situation, and is fairly unbiased. Of the three mentioned here, Hebrew is arguably the most successful "graduated" language — if you consider it a conlang to begin with.


What tools exist for creating syntactically correct generated text in new languages?

It is difficult for a machine to passively understand a language (it takes tons of time with machine learning, and that's for Google). Actively, that's even more difficult, as many machine responses are pre-programmed and rarely actually generated (and in that case, mostly nonsensical, but the question isn't for sensical utterances). It will be extremely difficult and without appropriate backing impossible to make one that learns a new language.

That said, the one like the Toki Pona in your question could be made. But you'd have to program most of it yourself, and in languages like Toki Pona that's easy. Try generating artlangs which more like natlangs.

This doesn't mean it couldn't seem like one. You could:

Extract text (in English or some language) from books or such. You can find enough text online.
Translate it (i.e. Google translate) between many languages, obscuring the information. (optional)
Translate it from English—or better, i.e. Lojban, Esperanto, Toki Pona or raw predicate logic, as they are less complicated and easier to translate from—to your conlang.
Dispose of invalid sentences using some kind of lightweight parser. (optional)

I couldn't find any (good) generators, but you could have the first!


Is there a toki pona hieroglyphics font?

toki!

a, mi jo e sitelen tawa toki pona. nimi ona li linja pona. sina ken anpa e ona kepeken nimi tawa ni.

Hi! Yes, I have a script for toki pona. Its name is linja pona. You can download it by using this link.


toki!
Toki Pona has a word for mercy, and it is simply olin, just like love, tenderness, warmth, etc.
For instance:

mi jo e olin tan sina

(I have mercy because of you),
or

mi jo e olin tawa sina

(I have mercy for you).


What features make a language easier to learn for people learning it as a second language?

It depends very much who your target audience is.

It is easier to learn languages that are similar to your own; as a German speaker, learning English is not that hard, apart from the grammatical features (aspect, for example) that don't really have a German equivalent. It's mainly a matter of learning the huge vocabulary with all its not-quite-but-almost synonyms.

Same with Esperanto. Grammar is easy, and most of the vocab is not too hard either. Here it's the particles which are the tricky bit.

I'm currently learning Dutch and Swedish, which are both similar to German, in some respects. No big deal. But both Arabic and Korean are a lot harder, and I gave up on Russian. These languages are very different from German, and thus harder for me to learn (the different alphabet is not the issue).

Klingon is hard for me to learn, because it has a different sentence structure (OVS, as opposed to SVO). If my native language had OVS as well, for example Apalaí or Hixkaryana, I think I would find Klingon much easier. Especially since Apalaí is also agglutinative, like Klingon.

There is a list of languages ordered by difficulty (from the Foreign Service Institute). The 'easy' languages are all Indo-European, and the hard ones are Asian/Semitic. You can imagine that the same list produced by a Chinese or Japanese institution would look very different.

Languages have no 'absolute' difficulty, but only relative. So to answer your question, you can make a language easier to learn for people if you make it more similar to their L1. Which, I guess, is the reason why there is no universal 'easy' language that we all speak...


Does The Syntax Construction Kit cover any new material that isn't in the other conlanging books I've read?

I will attempt to answer this question, despite not having read the book, so please take my advice with caution.

Looking at the website of the book, zompist.com/syntax.html, you can see an outline of the contents. Rosenfelder describes the book as "a tour of modern syntax".

Being a linguist myself, it looks like the book I'd loved to have had while at university. It covers (English) syntactic theory in a way that looks interesting and not simply dry and theoretical -- he supplements the book by a set of interactive tools to develop your own grammars based on the theoretical ideas of Chomsky and others. He does follow a particular strand of syntactic theory, which is mainly common in the US, not so much in the UK, but he also covers some alternatives to the Chomskyan approach. Rosenfelder's own view of Chomsky is nuanced and somewhat sceptical: he has an essay on this on his website (which I wholeheartedly agree with). Note, however, that this is about English, and these formalisms have been developed by linguists working mostly with English, so if your conlang is very different, they might not easily apply to it.

Apart from Chomskyan Generative Grammar, he also talks about Markov text generators, which would be useful to generate (random) texts in a given language. This might be a useful tool to practically explore your conlang: generate some text, and try to translate it. Several other tools are also aimed at generating sentences, rather than just analysing them. The meaning is often a bit random (as it is not really controlled), but at least the grammar will be correct.

So this is basically a syntax textbook, which will introduce you to syntactic theories while playing around with the formalisms and actively doing syntax (which to me is the best way of learning about them!) If you are interested in grammar, and the formal properties of different types of grammars, this looks like an ideal book. In fact, I have put it on my wishlist with a well-known on-line book retailer.

However, if all you want to do is build a smallish conlang, which might not even have a very complicated grammar, then this book looks like overkill to me. On the site he mentions that there is "a chapter on how you can apply all this to your conlangs". So conlangs are not really the focus of the book, but more a possible application of the described syntactic apparatus to invented languages. I would assume -- from the description on the webpage -- that this is a fairly advanced book, which is great for linguistics students and  for serious conlangers who want to make use of sophisticated formalisms when describing their languages. In that sense it will not cover too much of the same ground as his more 'applied'/'practical' books about language creation. If the previous books have kindled an interest in linguistics, though, and you want to know more about approaches to syntactic description, then this might be the book for you.


According to the Font of All Knowledge, Simlish

  worked best as a "language" made up of gibberish words that could not
  be translated, so that the dialogue's meanings would be left open to
  the imagination of the player.

and that William Wright, the Sims creator, intended it to be that way.

Here's a good Youtubeumentary on the topic. The voice actors, the audio director, they aver that it's gibberish. Meaning or emotion without form: while some words and phrases may have acquired "meanings", it doesn't seem like they've actually acquired "translations".

For example, if an English speaker says sulsul means "hello" while a French speaker says it means "bon jour", that doesn't mean hello = good day. All three are greetings, and I think that's rather Wright's point: sulsul has acquired universal meaning without actually acquiring a specific translation.


Klingon: does anyone actually use pIqaD, or is the Latin transliteration sufficient?

The official Klingon orthography according to the Klingon Language Institute is the Latin transcription. It is what Marc Okrand, the language's creator, developed and uses.

The Klingon script used in from Star Trek: the Next Generation on, known as the Okuda script (Michael Okuda was the set designer for Next Generation), is used, but it's worth noting that while the sounds of Klingon have been mapped onto these letters, the movies and shows just put random jumbles of letters on signs and things (this may not be true of Star Trek: Discovery, however -- I've heard they may actually have translated the signage). It's also not the only Klingon script to have been used -- according to an article in HolQeD, the Klingon Language Institute's journal, the 1980 U.S.S. Enterprise Officer's Manual (now out of print) featured a completely different Klingon script, though this one was a mere way of encoding English text rather than being mapped onto Klingon phonemes (Okrand did not publish The Klingon Dictionary until 1985, after all).

Given this sort of background, you can by no means take for granted that the Okuda script is the "real" Klingon pIqaD, even though it will be occasionally used to write Klingon. The Okrand transliteration is the only truly official orthography.

In any case, resources and activities written in Klingon are more often written using the official Okrand transliteration than with the Okuda script -- the Klingon subtitles on Star Trek: Discovery, for one example, are in the transliteration (can't make Unicode add new characters for such things, after all!) In general, you'll be fine with just the transliteration -- in fact, you may have an easier time, as the transliteration is easy to type. That said, no one will judge you if you use the Okuda script because you want the writing to feel less Terran or something.


I don't claim to be an expert on this, but I think it may be because that while tonogenesis is a "special" process, in that it produces a whole new dimension to the phonology (as opposed to something more "trivial" like clusters becoming new single segment phonemes), whereas tonoexodus seems to not be much different from other processes of loss in segmental contrasts. Yes, a sudden collapse of the tone system in a Chinese language, or any other language with a high functional load on tonal contrasts would be rather challenging to deal with, but so would any sudden collapse of significant scope, whereas a slow collapse, where contrasts are lost slowly, one after one, in some environments before others gives plenty of time to resolve any disasterous mass ambiguity with innovations.

I have tried looking around for examples of tone loss, and this seems to be the pattern I have been able to find. The Oto-Manguean languages with fewer tonal contrast that the reconstructed protolanguages seem to simply come from mergers of tones, either consistently or only in some environments (e.g. unstressed syllables) though the data is not quite clear[1].

Classical Chinese had 8 tonal categories divisible into yin and yang registers occuring respectively after voiced and unvoiced consonants, and into four different categories, ping, shang, qu and ru(checked syllables). While some modern lects such as Songjiang maintain all of these as seperate categories (Songjiang also retains contrastive onset voicing), others collapse the system in various ways. Beijing Mandarin collapses the yin/yang distinction of the shang and qu tones and merges ru into the other tones, while the relatively nearby Tianjin Mandarin keeps yin shang seperate, while merging yang shang with other tones. Along similar lines the different Chinese lects have radically different distinction-dimininshing sandhi processes, from the well-known relatively limited 214 > 35 / _214 rule of Beijing Mandarin to the complete loss of surface realisation of all but one dominant lexical tone in Northern Wu variants such as Shanghainese. Again, there does not seem to be any phonological compensatory measures associated with any of these losses of contrasts.[2]

Tonoexodus that isn't a simple collapse seems to be hard to find, though the Danish glottal suprasegmental feature stød likely originates in a pitch accent system (note that some dialects have pitch-accent and some collapse the distinction entirely), and it seems reasonable to expect that other collapses of a two-way tone system to a phonation system could be found. As for other things, the largely autosegmental nature of tone means that it doesn't leave much room for other segmental changes, however there seem to be a few cases of such influences, primarily on consonant voicing discussed in sections 2.6 and 2.7 of Yip's Tone[3] and references therein, though she notes that it has been argued by Thurgood that all such alternations are a product of phonation types (which may then coincidentally be associated with tone) influencing voicing rather than tone itself.

In conclusion it seems that the most likely process of tonoexodus is simply a slow gradual loss of contrasts in an increasing number of environments, with the associated lexical replacement/innovation that comes with language change, and a tone system evolving into something else rather than just being lost entirely is likely to become a phonation system, possibly with a minor influence on consonant voicing as well.


If you search for the researchers mentioned in the article, you can find some of their research papers. In those, they describe their methodology. In one paper that I looked at briefly, for example, they mention that they varied the consistency by making the placement of determiners random. (This is actually also mentioned in the Motherboard article).

Their research seems to be focused on finding out how children can learn languages, and what universal features of languages there are, so they up the difficulty of their experimental mini-languages by using rare elements, such as OSV word order (most (Western) languages use SVO). Discovery that some mini-languages are unlearnable is thus a side-effect of pushing the limits as to what are possible human languages. From a cursory glance at several papers I'd think that you can make a language 'unlearnable' if you add some random variation and choose a lot of rare grammatical features.

PS: in the Motherboard article they actually give a reason why no documentation of Sillyspeak is available: they want to avoid it 'escaping' into the wild, as its purpose is to be a completely unknown language to the subjects of the experiments.


Could a language with no voiced fricatives exist?

According to the World Atlas of Language Structures (WALS), a large database of various world languages' structural properties gathered from descriptive materials like grammars, around a third of the surveyed languages have a voicing contrast in plosives but not fricatives, and another third have no voicing contrast in either plosives or fricatives. Based on this, it seems that by raw numbers you're more likely to have only voiceless fricatives than you are to have both voiced and voiceless fricatives.


Is there anyone that has a conlang as their first/only language?

Yes. According to Wikipedia, Esperanto has 350 native speakers (data 1996). There is also a story about a linguist only speaking to his son in Klingon, but even though the child picked it up somewhat, later in life the child stopped speaking Klingon. Currently, he doesn't.

Also, see Esperanto native speaker AMA on reddit and a blog I enjoyed about speaking Esperanto natively.


How developed is the Old Tongue in the Wheel of Time series?

From here on Theoryland:

  Is there a complete language of the Old Tongue, and if so how long did it take you to develop it?

  ROBERT JORDAN
  There are basic 880 some words—maybe 900. I got a list of what is considered basic English—which are the 800 odd words of a basic English vocabulary. Removed the words that were of no use in the context of my world. Came up with words in the Old Tongue in each of those English words and then added those words that did have a specific context in my world.

Elsewhere on that page is an interview where he said this:

  What language is the Old Tongue based on? Gaelic, Russian, Spanish, Chinese, Japanese, Arabic and some additions of my own—bridging material, if you will. Grammar and syntax are a blending of English, German and Chinese, with some influences from a set of African languages, read about long ago and all but the oddities of structure long since forgotten. There are inverted constructions, for example (as in Mordero dagain pas duente cuebiyar!—literally, "Death fear none holds my heart!") and places where the article is omitted, especially where the word is a title or has gained enough importance to now incorporate the article; the absence of article indicates that it is the important or special meaning of the word that is intended. Though even then, it is not a hard and fast rule; the same inconsistencies of English are incorporated here. I am attempting to create a language which has grown, not one which was made.

It seems to be a complete enough language in terms of grammar and authentic enough for Jordan to use, though lacking in vocabulary.  From these quotes I get the feeling that he created the language well enough at one point that he didn't have to spend hours conlanging to be able to put a few sentences into his novels.

In the Wheel of Time Companion there was an English-Old Tongue dictionary, which is uploaded on Tor.com here.  At the beginning on the website (not sure if this is also in the book as I don't have it on me) this is written:

  While it is reminiscent of Tolkien’s ground-up creation of Elvish languages for The Lord of the Rings, The Old Tongue differs in that Jordan took a top-down approach, creating a dictionary of terms from which some basic suffixes, roots, and usage rules emerged.

I didn't bother scrolling all the way down or counting the words, but it doesn't seem to have much grammar aside from the suffixes and stuff.  Although we don't have access to this, Jordan seems to be implying that the grammar does exist.  All I could find was this on the Tar Valon library.


Sonority refers to the amplitude of the sound signal; ie the louder a sound is, the higher it ranks. Vowels are loudest, as they are voiced and generally less constricted than most consonants. Within the vowels, the open ones (eg /a/),  are louder than the closed ones (/i/, /u/). Then laterals, nasals, fricatives, and finally plosives. Within each of these groups (where applicable) the voiced variant is higher than the voiceless one (eg /g/ > /k/, and /d/ > /t/).

This matches the ranking in your image, so I would say it is correct.


Has anyone analysed the invented languages in the Earthsea books?

There is some information on one of them, Hardic, and a fragmentary word list.


Has anybody come up with a "Japanized" version of toki pona?

There's a list of Chinese symbols that can be used for toki pona words on the official toki pona website. I know I saw something on Reddit about a week or two ago that said that there was somebody trying to create a mapping system for kanji for toki pona, but he hasn't uploaded a finalised version from what I've seen.


Is it reasonable for numerals to behave like verbs?

One clear-cut example of a language that treats many things like predicates, numerals included, is Khoekhoe.

Khoekhoe marks many kinds of predicates the same way, including numerals. The paper argues that all three of the open word classes (nouns, verbs, and adjectives) in Khoekhoe can be analyzed as primarily predicates and non-predicative usage requires more morphology, specifically person-number-gender (PNG) affixes. Nominalizing stuff with a PNG clitic is extremely productive in Khoekhoe.

Here is an excerpt from page 3 of 21 from Predication and NP Structure in an
Omnipredicative Language: The Case of
Khoekhoe by Michael Hahn.

  Khoekhoe is an SOV language. The V slot may be occupied by a word from
  any of the three open word classes: a verb (1a), an adjective (1b), or
  a noun (1cd). Both commons nouns (1c) and proper nouns (1d) can be
  used. Even deictic elements (1e-f), numerals (1g), and possessives
  (1h) can act as predicates. While the choice of the TAM marker depends
  on the predicate, the syntactic behaviour of the different predicates
  is entirely parallel:

Here are some examples from the paper.

1a) saa=ts  ge   ra  |khii
    you=2ms DECL TAM come
    You (m) are coming.

1b) om=s      ge    (a)  kai
    house=3fs DECL  TAM  big
    The house is big.

1c) saa=ts    ge    (a)  gao-ao
    you=2ms   DECL  TAM  king
    You are a king.

1d) saa=ts    ge    (a)  Petru
    you=2ms   DECL  TAM  Peter.
    You are Peter.

1e) om=s      ge    (a)  nee.
    house=3fs DECL  TAM  this
    The house is this one.

1f) tii=ta    ge    (a)   saa
    I=1sg     DECL  TAM   you
    I am you.

1g) tara=di   ge    a  !nona
    women=3fp DECL TAM three
    The women are three.

1h) om=s      ge    a   tii
    house=3fs DECL TAM  mine
    The house is mine.


How can I format a dictionary that mixes vertical and horizontal scripts?

If you have a situation where the entry in the conscript is taller than the textual material discussing it, you’ll have to accept ‘wasted’ white space filling out the rectangle. Really, the only sensible way to do this if your textual material is in English is to have your conscript entry run down on the left edge of the rectangle, and fill in the English on the right.
If you have an alternative horizontal orthography (even if it uses the same characters, like happens in Chinese and Japanese), I would recommend using that for the dictionary/lexicon.


What is the oldest known constructed language?

The oldest language whose creator set out to actually invent a language (as opposed to Pāṇini, who wanted to create a classical standard out of an already  extant language) was probably Lingua Ignota. The formerly brilliant Langmaker website had an article on it (now accessible through the Wayback Machine). It was made in the twelfth century, predating another early conlang, Balaibalan, which was made somewhen between the fourteenth and sixteenth centuries.


This was not easy to find!

A bit of jazz Semitic auxlanging going on here.

Ayvarith seems to be an invented language based on Hebrew, Arabic and Aramaic.


Is there a specific term for a substitution cipher language?

"code" or "coded language". Probably mostly used in conjunction with sign languages, where the signs replace the (spoken) words (e.g. Signing Exact English as opposed to "natural" signed languages), but also for "encoded" spoken languages (either by relexification or phoneme substitution).