I've just tested out the Starwing 2 conversion patch, and it is actually missing something: it's not in 50hz... but 60hz instead. Which is not right...
I'm sure it will be fixed in no time ^^
Edit: Also, in both official versions of Star Fox 2, Snes9x doesn't emulate all the 3D graphics properly. For example, Andross is missing some polygons in it's second phase on hard mode. Is there any better emulator that can emulate that properly?
Well, it's a title hack and not a PAL conversion.
If you want 50Hz you only have to hexedit the region byte in the rom header and fix the rom for region checks.