You’re right the IR recording sketch works with a few minor tweaks on the Core. I updated my git repo with the Core version of the code.
The blog you linked got me reading more about the NEC protocol (which my AC units use) and summing each mark+space pair does make it much easier to determine the bit string. It looks like the Frigidaire controller is sending 32bit NEC codes with a repeat code, though some basic testing has shown that repeat code isn’t required by the AC units.
All of that will make capturing and programming the codes MUCH easier.