Not saying this is something that’ll be in the game, but if it were, here’s how I’d do it.

Given a certain speaking character and a spoken line, if the player does not know the language the speaker uses, the line could be replaced by a vague reinterpretation. For example…

“I am Caquot Seggunullung. Prepare to die!”

Depending on how much of Bloody Belchbutt’s language the player character understands, this could become “he says something you don’t understand, but it sounds threatening enough”, or maybe “he says something you don’t understand, but you believe it involves death, and probably yours”.

Basically, you can pick the overall tone from certain key words like “die”, and work from there. By the same token, you could have the reinterpretation mix up given directions.