I ran across a fanfiction database sometime recently, and I think the translators were explained in it. Maybe a tech room type thing, I don't remember. Anyway, I think that in normal conversation the translator is a voicebox attached to one of the speakers, of either race (usually worn by Vasudans), that broadcasts a translation and translates all speach into an earpiece. On a Vasudan ship, I guess the terran would wear the "squawk box" since he would have to translate to all of the rest of the crew. Anyway, on a fighter, I'd think it would be part of the comm, and inside the cockpit where if it were hit by weapons fire the pilot would be dead anyway, so I don't think making it a subsystem would be practical.