The script code works exactly as intended. It changes the selection mode at any time.
I understand you want your workflow preserved, and many others do too. Just look at the topic Take layer state into account in the undo history
That’s why I tried to give you a compromise. A different set of shortcuts (not perfect) but at least you workflow stay mostly preserved.
I was wrong!!! I could just open Krita and checked.
It already has these shortcut implemented in Krita, just need to configure. No need for external plugin or scripts.
Cheers.