I don't get it either! I hope someone who does know replies to this because my favorite singer is Korean and I have no idea what is going on with him and I kinda want to know.
I know that you can sign up to be a translator for Twitter right now. I think they are doing some sort of trial and error thing and that's why they keep putting the translate option up and then taking it down. Anyway, it's annoying. I hope they get it working for keeps.