I tried with QShortcut earlier with no effects.
I didn't checked activatedAmbiguously, but manual says
This signal is emitted when the user types a shortcut key sequence that is ambiguous. For example, if one key sequence is a "prefix" for another and the user types these keys it isn't clear if they want the shorter key sequence, or if they're about to type more to complete the longer key sequence.
so i'm not sure if this is my case, my shortcuts are not ambiguous, they are rather overridden(but i have to admit that i didn't actually checked it)

My last solution
Currently widgets reacts on shortcutOverride(in eventFilter) event and global shortcut checks focused widgets and works only if focus is on centrain application dependent widgets.
was accepted so i'm working on other tasks now, lets say current implementation is good enought and don't have to be ideal.

I'll try to check activatedAmbiguously signal when i'll find some free time and i'll let you know if it helped.