Hello,
I have Sailfish OS installed on a Sony Xperia 10 II. Now an app (LadyCycle) for Android can not be switched to German. Sailfish OS is localized German whether and where you can make settings for Android I have not found.
The app itself offers a language selection but it is not used. It appears with a language selection the note:
Android 8.0 and higher demands that you change the system language to change the language in the app.
With Sailfish OS on the Jollaphone, the app still ran in German.
Greetings
Sebastian