The Sonic 3 cartridge contains an FM1208S FeRAM chip for storing its saves. This chip is no longer produced, but a similar, higher-capacity chip, the FM16W08, is. By pulling the extra address lines to constant levels, we can pretend the new chip is only 512 B like the original. Since the new chip is a small(-ish) SMD, the old one was a huge 600 mil 24-pin DIP, and their pinouts are similar, making an adapter board is simple.
I tried to make your pcb as kicad.'cb its and the error deletion file with errors you saw