Yah honestly have barely dug into the code despite somewhat understanding some of it
. I just happened to also have this problem before where I burnt off one of my motor pads and had to get one of the other outputs to act as a motor output so lesson learned the hard way on how to get resource mapping to work.
If you jump into the CLI mode of betaflight configurator app and type "help" or "diff" or "resource(s)" can sort of glean a fair amount of info from all the parameters that are setup in the firmware that get shown there, basically configurator is just a graphical interface for setting all the parameters you can see listed out there and there's even more you can tweak from the CLI mode. Mostly built up some knowledge in this arena watching JB vids and googling and ending up on Oscar Liang's site.