I'm not aware of anyone even bothering to try to reverse engineer the code. Nobody really seems interested in bothering with xbox hacking/modding post 360 days.
I agree the "self healing" thing is a bad idea. It doesn't fix anything, it just borrows accuracy from one area to give to another. Same with those solder on circuit potentiometer boards, they just steal from the outer circularity to give to the center accuracy. "Intermediate op-amp mod".
If you replaced the modules (or even just the potentiometers) with similar graphite based ones your only option to "calibrate" afterwards is to solder in small low value resistors between the potentiometer legs, where appropriate. Value is based on what % off center it is. This method doesn't seem to steal from the outer circularity. There are videos on youtube regarding this process.
If you replaced them with Hall Effect modules, the Hall Effect modules have to be manually physically calibrated, again also there are some videos on that process. Personally I thus far have only upgraded joycons and dual sense controllers to Hall Effect. I have read though some people saying that the Hall Effect sticks interfere with the Hall sensors of the triggers. However I have also come across still yet other people saying they haven't had a problem with that.
Would be cool to have a software based CFW way to solve this. Soldering in the tiny resistors isn't too much trouble but...it would definitely be cooler to just plug it in flash the chip and be done. But how would one dump the OFW and flash the CFW? Pi Pico maybe? TTL maybe? Only thing is you'd have to block official firmware updates, and who knows if CFW on your controller could net you a ban from xbox live, unknown. Interesting thought, good luck.