Reporting back to the community:
After a lot of tweaking, the PLC01 works well!
I have it connected through an appliance module. I turn the PLC01 on at the beginning of macros (or after dimming sequences), and I turn it off at the end. This is done to overcome PLC01 incompatibility with CM15A.
I also have a repeating schedule to turn the PLC01 off from my WM100 in case PLC01/CM15A floods the grid with "infinite chatting loop". An alternative solution would be to buy a short-time timer that would power cycle PLC01 every few minutes. This is needed because when PLC01/CM15A start chatting there is no stopping it other than unplugging PLC01 from power.
As you can see there is a lot of tweaking, but the macros are working flawlessly now with macros signal reaching every room (including rooms behind GFCI).
(Ultimately I will invest in XTB-IIR)
S.