Everything you need to know about chat is in this Dev Journal on Communication courtesy of Vye.
Basically, yes. It will be gibberish, unless they both share a common language. If one of them is slightly proficient in the same language as the other, then they get some gibberish, some not gibberish. And yes, gestures are planned to bridge that gap.
Only thing is if you have someone speaking gibberish at you, their gestures might be hard to get a point across.
