How to make lang work?

You'd change your language in-game by using the the "/lang zn-ch" command. Geneally I would suggest keeping the names to two characters though.

thanks.sir
I have tried,but it didnt work.
it only support en lang.

So please support more lang.
thank you.

Looking at the source, the developer would need to properly utilize the Lang API to supply the player's ID when sending messages. For log/console output, that would default to your server default and generally wouldn't need support for more than one.