Yep but i'm not the only one to know that and most of all Hiroaki Hondo one of the CPS2 engineers was doing his stuff on X68k. The CPS 2 is a hardware that use encryption + an extended color palette that's all and greater sprite size.
The CPS board have just Qsound chips but try to play final fight or Street fighter 2, the sound is far greater on X680X0 versions !!
I can even upload the emulator + games in the zone if you want to give it a try hehe
"don't forget there are many X68k all around Japan" (copyright capcom 1987) so yes document yourself about CPS SDK you'll find it was running on X680X0
X68k were just more than conversion or ports, it's the machines capcom developpers used to create the games we love.....