Inric has a lot of vocabulary to learn :) I did toy with the idea of putting the words he doesn't (yet) understand in code of some kind - rot13, or a different font. But I thought it seemed a bit too gimmicky, in the end. It's a good thing he learns quickly.
You could put your language/world markers around the words he does not yet know, that would work very good, I think.
I have enough trouble fitting the text in as it is ;)