In version 3.7.4 of KStars the language cannot be changed again (like in 3.7.0) and uses the system language, similar to #485944, https://bugs.kde.org/show_bug.cgi?id=485944 Tried to change within "Hilfe - Sprache einrichten" (Help - Switch Application Language). After a restart of KStars the settings are ignored and the language of the OS is still used. Systems I tried Windows 11, Linux Mint 22 and a compiled version of KStars on Raspberry PI 4 Bookworm with the same result.
Should be fixed in 3.7.6