I don’t get it, why doesn’t she want to use magic to understand them? Why did she act like it was some sort of sin to have done it before? Isn’t understanding more about your situation and communicating with the people around you basically the most important thing right now?
Ah, I get it, so her language magic isn't like "once actived, it's all done", but she has to activate & maintain it consciously, whenever she wants to use it. Is it because of that? Does it take too much stamina to maintain it?