Thanks for the feedback, at first you can't use the tongue, I think that is the problem you are referring to, but if after you talk to the second npc it doesn't allow you to use the language, there is a problem, Can you confirm if this is the case?
I had the same problem and this explanation helped. Think an on-screen prompt "press space to interact" or even just "press space" that pops up when you're at the first npc would solve everything.
