Now that the game has opened in Taiwan and Hong Kong, bilingual players probably would like the option to converse in Chinese. The good thing is there already is a Chinese IME in-game, called up by CTRL+SPACE (this may depend on your OS IME settings too), the bad thing is you can only use a subset of the characters. I'm not sure what the problem is but the game will highlight characters you can't send and tell you so. There doesn't seem to be any pattern to the usable and unusable characters, it's not like a word filter. My guess is that it's an encoding problem, i.e. some might be Unicode but some are not.
Also, you used to be able to paste in Japanese into the game, and now it'll say you can't send out the words. Strange things.