The best solution would be to change the software code in the game to make it compatible with the SGM when used with the F18a. Lot easier then changing the hardware design.
That's ridiculous. Mecha-8 and Mecha-9 work on original hardware, and that's what the games are meant for. If they don't work on alternate hardware, then that's the fault of the alternate hardware.
Remember the standalone ADAM computer is only 99.9% compatible with ColecoVision cartridges. Defender and at least one other game cartridge does not work correctly for the standalone ADAM. The solution was that someone back in the 80's made software changes to Defender so that it would work with the standalone ADAM.
I'm not aware of any version of Defender (or Super Cobra) that was released in the 80's that fixed the issue with the ADAM. Otherwise the ROM would have surfaced by now, and nanochess wouldn't have had to create the fixed ROMs of those two games.
Also, Mecha-8 and Mecha-9 work on the original ADAM. It is not the responsability of homebrew publishers to make their software work on every homebrew variation of a game console. They can try if they want to, but I for one would never guarantee that Team Pixelboy games work on the F18A, or anything other than legacy hardware.