No traeger says "we had a vote , and Predator sounds cooler" That means they made that name up.
Common name in English.
So Traeger managed to nickname the Predator what the Predator also called itself in its own language and that's also Predator?! Maybe I'm missing something here.
You are. I'm really, really not sure how you're not getting this? It's not difficult.
The humans have decided to call them Predators, so when Rory reads whatever word Predators use to refer to themselves in their language, he translates it into "Predator" in English because that's what humans have decided to call them
. That doesn't mean the word is actually "Predator" in their language.
I'm sure dolphins wouldn't refer to themselves as "dolphins", but if we could translate their language, we'd translate the series of clicks and chirps they'd use to refer to themselves as "dolphins" because that's what we call them in English.
And yes, he does translate it. He reads it off the screen.