Thank you dink, I got the 32-bit build, I did an input replay with a scaling algo enabled for Contra and Neo Bomberman (Stage 1) and it worked like a charm, Metal Slug X gave a warning error on launch (Error reading 250-c3.c3 from mslugx) and it gave graphical glitches, but maybe it's a rom/bios issue.
Edit: MS3 worked correctly.