We can’t agree on how to spell the name of the famous Dutch/Flemish painter(s): were Pieter B. the Elder and his relatives Breughel, Brueghel, Breugel or Bruegel?
As is often the case with foreign names in English, we’re not entirely sure how to pronounce them, either.
In Dutch this name is pronounced ˈbrøːɣəl (subject to the usual regional variationː possible diphthonging of the stressed vowel and devoicing of the velar, not to mention the variability in the second consonant), which is what you would expect for a spelling with eu. In turn, you would expect foreign-language ø(ː) to map onto nonrhotic English NURSE, as happens with French deux dø mapped onto BrE dɜː or German Goethe ˈɡøːtə onto BrE ˈɡɜːtə.
Yet on the whole we call the painter not ˈbrɜːɡl̩ but ˈbrɔɪɡl̩. Why?
I can only suppose that our usual pronunciation is based on the spelling with eu interpreted according to the reading rules of German. If Deutsch is English dɔɪtʃ and Freud is frɔɪd, then Breug(h)el must be ˈbrɔɪɡl̩.
For the same reason, even though Wikipedia prefers the spelling Bruegel (which would prompt us towards a pronunciation ˈbruːɡl̩), most of us, I suspect, tend to spell the name with eu.