I don't know if Pootle has been used with a non-English source
language yet? Pootle devs?
I am not yet aware of someone using our tools with non-English source
language. The problem with plurals was mentioned on the Debian list. I
think our tools should correctly decode the non-ascii msgids according
the character set in the header, although this is not tested, of
course.
I think I have seen some msgids with things like smart quotes which
won't be present in 8 bit character sets. Most tools could probably
work
with it without problems.