If you were to type >mame -listxml at the command line, you'd get lots of info about the games and the roms they need. That xml file is just that output - just in case you want it for something.
Get the latest MAME 0.254 from https://mamedev.org/release.html (this version will be there in a day or two). It has the blue M icon. Your existing roms will be a 90-95% match. If they work with the particular games you want to play, then there's no need to update the ones you never use. If you find...