  Recent observational studies aiming to quantify the molecular cloud lifecycle
require the use of known 'reference time-scales' to turn the relative durations
of different phases of the star formation process into absolute time-scales. We
previously constrained the characteristic emission time-scales of different
star formation rate (SFR) tracers, as a function of the SFR surface density and
metallicity. However, we omitted the effects of dust extinction. Here, we
extend our suite of SFR tracer emission time-scales by accounting for
extinction, using synthetic emission maps of a high-resolution hydrodynamical
simulation of an isolated, Milky-Way-like disc galaxy. The stellar feedback
included in the simulation is inefficient compared to observations, implying
that it represents a limiting case in which the duration of embedded star
formation (and the corresponding effect of extinction) is overestimated. Across
our experiments, we find that extinction mostly decreases the SFR tracer
emission time-scale, changing the time-scales by factors of 0.04-1.74,
depending on the gas column density. UV filters are more strongly affected than
H$\alpha$ filters. We provide the limiting correction factors as a function of
the gas column density and flux sensitivity limit for a wide variety of SFR
tracers. Applying these factors to observational characterisations of the
molecular cloud lifecycle produces changes that broadly fall within the quoted
uncertainties, except at high kpc-scale gas surface densities ($\Sigma_{\rm
g}\gtrsim20~{\mathrm{M_{\odot}\,pc^{-2}}}$). Under those conditions, correcting
for extinction may decrease the measured molecular cloud lifetimes and feedback
time-scales, which further strengthens previous conclusions that molecular
clouds live for a dynamical time and are dispersed by early, pre-supernova
feedback.
