Форумы / Cotonti / Localization / Transifex translation service

2 points:

• Changes in the code a backwards-compatible. All existing plugins work as before.
• There's a convertor tool for the main package langfiles which automates 95% of changes that need to be made in langfiles.

Added 3 days later:

Now our language files are compatible with Transifex and I've written a small guide how to translate them in bulk here.

Added 3 minutes later:

FYI: all the existing and old language files should work just fine without any problems. And nobody is forced to use Transifex, you can continue maintaining language files in your preferred way without much changes.