>>280592862
>Also when she and her mom speak English, the audio sometimes switches to Japanese.
It's easier to comprehend in the original where they use horizontal text in such situations.
In order to adapt that they'd have to first voice it in the original language and then dub over it in Japanese. Seirei Gensouki recently did that and it was rather annoying.

>>280527167
>>280540037
That's one of those things that work better in manga than in anime.
When she's talking alone with her mother, the text is horizontal, indicating they are speaking in a foreign language (i.e. English) and not Japanese.