> Is there something wrong with my ROMs that I can fix,
> or is this just telling me about ROMs that _nobody_ has good dumps of?

The numbers of bad and nodump roms is correct. It's the number which mame provides. You can't change them unless you redump the original arcade board and send the roms to mamedevelopers.
The missing roms x (x are nodumps) can be ignored. You can replace the missing nodump roms with dummyfiles though. Scanner->nodump handling.