Through listening to some sound clips over on tumblr regarding Optimus Prime speaking "The legend exists" in Cybertronian, I was able to write down the words (not english, mind you) and try and make as much sense of it as I possibly could. This was what I was able to determine instead of it being jumbled up electronic gibberish back in the first two movies. "Fostomimas etoma gwa." (gwa could've been "gua" but I don't know) It could've been more seperate words, but I don't think that would make any sense at all. I tried to hear as much as I could, but if anyone can think of a better way of writing down the words themselves, you can try. This was just what my ears were able to hear. Sorry if it sucks, but I tried.