OK, good to know other software also use the concept of 0…n shortcuts. But yes, the GUI looks very old-school and cumbersome 
I have now made some experiments. This is my current suggestion how this could look in the workspace settings dialog:
Italic text means that the shortcut is not overridden so the application default value is used. Bold text means the shortcut is overridden by the user, and stored in the workspace settings file. The default value is always visible as tooltip.
Qt supports this out of the box, even in parallel to “normal” shortcuts 
. See the “A,S,D,F” shortcut in the GIF above.
Is this really needed? The shortcuts will be stored in the settings.lp file in the workspace which can easily be copied between different computers. Is there any other use-case for a shortcuts export/import feature?