Poe also understands BB8.
I think the biggest issue (not that it really bothers me but worth mentioning) is that Rey understands BB8 immediately. Luke needed an x-wing translator at first (and always? or did he not need it in ROTJ? I can’t remember) and Poe worked with BB8 a long time (presumably).
Of course Rey worked in an outpost/spaceport thingy so you can assume she’s been exposed to all sorts of different languages, which I guess is why it doesn’t really bother me anyway.
Not ROTJ, but TLJ.
After I posted that we went to see TLJ a second time and yeah that stuck out to me lol. Hadn’t really even thought much of it the first time.