If you are on Android 13+ you can go to your phone settings -> System -> Languages and Input -> App Languages -> Jerboa for Lemmy and set the language here to English.
Nochmal auf Deutsch:
Systemeinstellungen -> Sprachen und Eingabe -> App-Sprachen -> Jerboa für Lemmy -> English
I have the same problem and would also prefer English over German. I'm still on version 0.0.33 so I at least don't have the text below the icons on the bottom. I too haven't found an option to change the interface language in the app.
In the browser version there's a possibility to select the preferred interface language but after choosing English there it didn't change anything in Jerboa.