Earlier quoted context omitted.
I also have this problem with apps in my native language. I have my phone set to en,no because I prefer the English version over some bad auto-translated crap where some apps try to translate stuff. But then when I download a Norwegian app, then it prefers to use some badly maintained English translation instead, but here I would of course prefer the native version. Can't win.
On iOS, this is something you can can control on a per-app basis from the (system) Settings.app.
And for some reason, Apple/iOS doesn't allow you to set this for some system apps. For example, Music (Apple Music) app on iOS doesn't offer this option, which I desperately need because I don't want the music metadata I listened got translated.