I have tried soldering P13 knock board into P30 ECU, and was getting unknown CEL 24. Maybe my P13 knock board was fried or maybe they are "incompatible". I'm going to try to solder the board into JDM P72.
Better late than never.
It could be a bug in Hondata. In JDM ECUs D12 is routed to a different pin hence a different port address, so if ECU firmware does not check for JDM/USDM-ness then it won't read the right port.