I would just add a little thing. Common words should have almost all the time the same alternate form, at least in the same session.
If a character hear a word and the player guess what it means and remember its meaning, I think the character can do it too. It demands only an effort of the player to search where he saw this word before.
If we got the sentence: \"Did you see the green tyranosaurus rex killing the other green tyranosaurus rex with the legs of the dead red tyranosaurus rex?\"
We should read something like: \"Did you see the jiki loumbadorth poer ginith the other jiki loumbadorth poer with the legs of the dead red loumbadorth poer?\"
Ok, it\'s a ridiculous sentence, but it\'s only to show that we can understand that the person speak of something doing something on another thing like it with the leg of a red thing like it. Sounds weird, but we can have an idea of what the other said.
What is interesting too is the possibility to speak slowly to be understood. We can say: \"Did you see the gre en ty rano sau rus re x kil ling the other gre en ty rano sau rus re x with the legs of the dead red ty rano sau rus re x?\" It\'s not much more easy to understand, but it would works.