Thanks for all this interesting information, Scribbling Turtle!
Do I understand correctly, that you did have pressure sensitivity when using the portable version, but didn’t with the normally installed version? (until you did the qt.conf trick)
When you activate the “use the Pen as a mouse in some Apps” option, doesn’t that affect the quality of your pen strokes? I mean, do you lose pressure or input resolution? Or does it have any other negative effect for you? From what I can see in your video things look normal – but hard for me to tell really.