Adding a language for translation
Fragment of a discussion from Support/LiquidThreads
Strictly speaking you will need to translate 18% of the Mediawiki core messages to start exporting to MediaWiki. This is currently 544 messages, which is 66 more than the 478 most-used messages. See FAQ. Also, if one or two of the most-used messages are very very difficult to translate, then you could translate more of the core messages instead, for now, and return to the difficult ones later.