Changes
/* RET cc and WAIT_n timing analysis */
IO_ACK offset into INT (interrupt) should not implicated by WAIT_n generator, and it seems that a WAIT_n during T2 is ignored because of autowait already inserted at this moment... for synchronizing an IO_ACK, I have normaly to insert WAIT_n during T2+2.
http://www.cpcwiki.eu/forum/emulators/cpc-z80-timing/ : ~ a WAIT_n does not use RAM access, so does not slow down a "CPC instruction" (hypothesis)
In doc, IO_ACK begin after T2, during the two autowait inserted. So no way to detect that an instruction is IO_WAITing before slowing it following "slow down" instruction timing table.
