That website has a lot of good info, but it’s missing quite a bit too. For that I need to be able to see on the wires using a logic analyzer. That’s what I did for the signal strength and volume control. If I wasn’t able to do that I never would have gotten it, that website is missing some of the critical info needed to make this radio work.
I may be able to write an Arduino sketch that could sniff the wires and log it somewhere, basically acting like a logic analyzer. Would be you willing to solder 3 wires on your radio PCB if necessary? I’ll see what I can do first though.