My native language is Czech,
my username on Transifex is pavelb, translating most of strings in app texts:
(and trying to achieve complete translation coverage - that list of requests, pointed by
Joas is from me)
Also translating user documentation (Pierre was so glad to pushed implementing necessary workflow)
(And also aiming for more than year with Pierre for Client docs translation)
Trying also regarding showing already translated apps descriptions in app store.
The last remaining domain is website, so trying there too 