Hi.
I'm from poland and want try translate the playroom to my language. How to? I saw lng files but i thing it's uncomplete.

If you trail through the jungle of the foram you will find plenty of info about translations. Put more simply find a team, who not only can translate but are prepared to act as helpers. If you can translate from French to Polish you stand a better chance. Personally I don't see the point unless you regularly achieve 20 to 30 bums on seats (as they say in the trade) when anybody joins a future Polish PR. If there are numbers in single figures it will be less interesting for players wishing to join.

The LNG files you found are just the Windows client string, and most strings you need to translate are on the server. Thus, you first need to get permission from the developer to work on your language, and as Ynwa said form a good team of translators and helpers.