In KStars 3.7.9, the language cannot be changed any more, just like #505412, #497225 and #485944. The system language is used instead. Used "Hilfe - Sprache einrichten" (Help - Switch Application Language) to change the language but after a restart of KStars the settings are ignored and still the language of the OS is used. System is Linux Mint 22.2
The issue is fixed. The PPA is now rebuilding the package for 3.7.9 stable.