Good job.
Last precision, does it work on mother 4x with : (all connected)
-Playcity
-X-mem
-X-mass
&
Multiface 2
Or must i connect multiface 2 mx4 alone?
I have connected : XMem + XMass + MF2. Everything works.
I tested (the 3 connected without power supply on mother X4) :
1)Add Airwolf.rom in rom 03, with RMA in the xmem
2)reset
3) |airwolf from xmem --> runs well
4) Use "stop button" on multiface, "save", "program", "disc" -->new name on disc "airzolf"
5) reset on multiface
6) run "airzolf" --> game running
7) reset multiface, stop multiface, then chose "return" to make the mf2 invisible

run "airzolf" it doesn't work because the mf2 is invisible !!!! (normal)
9) reset mf2 , the mf2 is visible again
10) run "airzolf" --> works again...
Guess what

It seems to work all together for now. But i'm sure guys you will find something because i can't test everything i think.