As mentioned, her dialogue is very rude based on the archetype they are using for the character, but at least for me it's more about her confidence and being rebellious against the authority, which to be fair can be associated with foul mouth, but then she is not stupid either. To put an example , based on her context I could see her calling a guard pig, but not motherfucker because of the consequences it could have to her mates. Same with the mother, because at least the impression in english to me is that she hates her completely, while in japanase is more "I don't care, I'm doing my way"
With that said I don't thing is a bad thing, it's just more of a case of "whoa, those subs definitely don't match the audio" thng