These days Python 3 is the standard so we should convert it. The tlwebadm bits were converted on bug 7554 but the activation script still needs conversion.
Tested with Xfce on Ubuntu 20.04: ✓ Configuring in tlwebadm still works ✓ Application group selected by user ✓ Application group selected by profile ✓ Application group for other user ignored ✓ Application group with desktop icon Seems to work as intended. No complaints in the log either.
Tested with Xfce on Fedora 34: ✓ Configuring in tlwebadm still works ✓ Application group selected by user ✓ Application group selected by profile ✓ Application group for other user ignored ✓ Application group with desktop icon ✓ Non-ASCII name for application and menu Works just fine!