I read somewhere that some of these that were dumped are the expensive, rare versions and are easily programmable into old, non-rare versions. That's one of the reasons these aren't released. Not only that, I'm sure the internal ARM7 roms aren't dumped for these, so even if they are released, the odds of them being in working order are very small.
there is not much scerets left on IGS027A...
it is easy to get most of them (games before theglad?) dumped via trojan
but the newer chips(theglad/svg/killbldp...) use an eXecutable Only Memory region at the start, ~0x200 bytes, varying from game to game. Even for these game we can get the internal rom dumped and patch it to get game boot and play, not so hard ...
(I dont have idea about those CAVE game as I dont have PCBs)