(something went wrong with the software i use to remap keys, was an easy fix but was trying to get something done in the terminal before investigating wtf was up with my keyboard)
@liiwi @molly0xfff
Another nice utility of this kind: https://github.com/rvaiya/keyd
I'm using it to remap "k" and "l" keys which no longer work to the ones I didn't use — plenty of these on this old MacBook Pro.
It relies on low-level kernel stuff so it's limited to linux only, but it's not limited to graphical sessions and remapped keys work in the console too.
I'm not sure how it would work with the modifier keys as I have never done that myself, but shouldn't be an issue.