Language packs should be placed in Effects, include the language code in its name and have the extension .fxlang. More than one language pack can be used to help cover a single language. See the basic language pack attached for an example. When creating a language pack, make sure the character encoding is set to UTF-8.
The code (v1.1):
Language pack repository:
If anyone wants to contribute, PM me your Github username. It might also be possible to suggest edits without being one, although i'm not sure.
Default language pack (v1.2)