I followed your guide and got Qtvkbd to work with Plasma Wayland under KDE neon 5.20. However, setting the variables you listed seem to break screen rotation in Plasma under Wayland. The screen rotation options under Display Configuration in System Settings is missing under Wayland when the variables are set. It returns when I remove the variables and log back in. There variables are also causing some scaling issues, most noticeablely with GTK app fonts being too small, on my hidpi display (Surface Pro 4). Is there any way to fix these issues?
Edit: I’m also getting random lockups with the variables set. Incidentally, one of the variables fixed an issue I had with the Application Dashboard being covered by my top panel.