Hi everyone, here my suggestion
If you have race / nationality option, you could transform chat text into something unreadable for people of other race except if he has the skill read the language. As the progression of this skill is better, you'll see more real words in the chat window allowing you to understand more and more what is written.
Some people could be interpreter. Very useful in politic games. If books are implemented, they can be flagged with the language of the writer, so you need to know the language to read it.
To learn a language, you must open books of the language you want to learn. Or everytime you 'hear' someone speaking in one language, you began to slowly learn this language.
That's the essence of my idea. I think it could bring a very special aspect in relation with other player, and foreign politics.