I was having problems with the background music stopping sometimes with my Satiator. I just upgraded the SD-card (CD music streaming with my old one didn't work at all), so I'm not sure that's it, but it is Nintendo branded lol. I haven't had a chance to try the Japanese version yet to see if it still does it.
Otherwise I didn't notice anything, but I haven't finished either game yet.
It's not an emulator. The Saturn isn't powerful enough to accurately emulate the Genesis with this level of performance. These games are native ports to the Saturn. An executable is loaded in and runs the game code, the ROM is just there as it's a convenient and easy way to store all the game's data. The Actual genesis code in the ROM is being ignored and isn't running.