I'd use English as the main language because it should be known to your translaters. From here you can ask them to create po files in any language.
I've just studied the translation example.
Is it correct that in the case above (English as main language) I have to have two files
with the English texts, app.po and app.en.po? Do I have to simply copy each entry
from app.po to app.en.po?
Another question: Without the po files, the program runs without errors, but
completely with English interface, correct?
So many questions ...
Thanx
stem