ALL: I don't think the "input" signal is repeated on both the red and black phases. If they were there would be double commands on the originating phase which the Activity log does not show.
90+% of commands sent via a wireless (HR12a) or any plug-in controller work well. Still the question is why do the RF commands to the Cm15a respond relatively reliably but the timers and macros are very iffy. I am also getting odd commands showing up. I have a few motion detectors on house code A. An OFF code on A4 generates an ON code on A5. This doesn't hurt anything as I have nothing on this code but I'm curious as to what is generating the command.
I don't have any experience with the XPCR, so I can't tell you if it amplifies the signal on the receiving phase or not.
As for the RF signals, do you have any other RF transceivers in your home? If you have another RF transceiver, it may be picking up the RF signal, and broadcasting it out with more power than the CM15A is doing.
As for the "extra" A5 codes, some of the motion sensors also have day/night sensors built in, which used the next higher unit code (or unit code 1 if the motion sensor was on 16).
So, if the A4 motion sensor is turning on a light nearby, then when the light on A4 goes on, the motion sensor thinks it is daytime, and sends an "A5 Off" command. When the light goes out, the motion sensor thinks it is nighttime, and sends the "A5 On" command.