UPDATE: I noticed the game count wasn't right after using GameEx Arcade Edition to generate the XML files, so I dug a little deeper and here's what I found:
Missing from XML files:
bnjm.zip (Bump 'n' Jump)
bublbobl.zip (Bubble Bobble)
junglek.zip (Jungle King)
mach3.zip (Mach 3)
punchout.zip (Punchout!)
Wrong in XML files:
splatter (Splatter House, mame ROM not present)
I have no idea why Splatter House was added to the list. I do not have that rom in the set I used to generate the list. As for the missing games, the ROMS are there and I confirmed those games are not in ANY list generated by GameEx. Getting the classification wrong for HORIZ and VERT lists is understandable, but I don't know why games would be missing from the ALL list. The only clone in that list is Pac Man, and it found that one no problem. The rest are all parent ROMS
UPDATE2:
A comment made in another thread got me thinking there was some default filtering happening in GameEx, so I went back and took a look at the advanced MAME settings. Sure enough, I noticed two things. There were a bunch of things in the "Filter" list, one of which was games from Japan. This will result in games being excluded even if they are in English and play perfectly fine, but have the word "Japan" somewhere in their title/description. Since I am only adding ROMS I already know I want, I don't need filters, so I cleared them. That got the missing games to appear in the list.
I than noticed there was a field that said "Don't filter these ROMS" and it included PacMan and Splatter House. I thought that was a HUGE coincidence since I mention both of those above. To test this, I removed the PacMan rom and regenerated the lists. Sure enough, Pacman was there even though the ROM was not. In my opinion this is a bug. That field should do a further check to ensure the ROM is actually there. I cleared that field and Splatter is now gone. PacMan is still there because I want it to be
Based on the generated output, I see no reason (other than developers' time/interest) why this can't be a standalone program. This would not hurt GameEx and would benefit PinbalX by not requiring the use of one front end to configure another. It would require the two programs to stay in step with the schema for the list though
Out of curiosity, where does the metadata for the games come from (manufacturer, full name, date, screen res, etc.)?