I would think that even if we could match Simlish letters, with an English alphabet, we don't know how anything is spelled, and what the rules of grammar are. I suspect, they haven't worked that part out, since it's not necessary to the game. I'm not sure that any sign in the game, is meant to mean anything. There might be a spelled word for Llama, though. As for the verbal language, I suspect that they do actually have that worked out, to some extent. That part actually does enhance gameplay, if the speech sounds natural, and is consistent.