See that is the part of the game that always confuses me. I mean in lore the “language barrier” doesn’t exist. I mean did you see a translator in the room when Anduin and Saurfang had their prison cell meeting? Hell how about the fact that in game we actually watch as Saurfang, Malfurion and Tyrande exchange words during the Darshore engagement.
Funny how that barrier seems to work at times 