As long as the MAME specific rom importer came up, it should be good. If all the names were changed from shorthand to normal, and you found metadata and media, you imported them right. The MAME Importer was the one during import that had all those check boxes about region and types of games. One of the check boxes is to not import known non-working games, but this is for MAME Standalone, not MAMEUI and the build could be slightly different, I don't know.
If you may need more help, we do have a tutorial on MAME. It's a bit out dated, some of the sections like about Lightspeed for example can be ignored because the software hasn't been updated, for it's still all there for the most part. Just replace what ever version of MAME I was using for MAME .180.