Unable to remap key ("reserved" keys)

The game won’t let me assign the key I want to the action I want. There are NO good reasons to reserve specific keys for specific actions, especially if said action can be remapped.

I had described the problem in the feedback forum (Key mapping problems), but I guess no dev reads it…

Platform is PC, Version is the latest on GOG, as of today 2021-02-24 (Orryx 1.10 GOG)