It's not a "fix". It's SA-1, and it's probably the most demanding chip in emulation. And there are two ways to do this:
a) The easy way: just ship the PocketSnes 65C816 C interpreter, which has been proven to work (and enabling it in DrNokSnes is just a reconfigure & recompile away).
b) The hard way: adapt the currently in use assembler 65C816 interpreter to also act as SA-1 one. Since this is the research project and the "proper way this is what I'd like to do when I find the time.