read the manual.
I provided the tools for you to potentially create a solution. Not a completed solution... I don't have an Italian keyboard for a start!
If you want to play with adjusting keymappings because you suspect this may fix your problem, then be my guest and use this tool. I don't have a completed solution. I am not even certain that this will in-the-end fully fix the issue. But there you are. you asked about .Xmodmap
(a local "defaults override file" I imagined), I provided the closest I had. xmodmap
itself. hope that helps
You will have to do some playing yourself to get a solution.
As it says on those toys at Christmas "Some Assembly Required"