@gerpy
ClrmamePro was absolutely daunting when I first tried it but there is an excellent "walk thru" video on YouTube.
It makes it so easy to figure out.
I used it and now instead of 4700 MAME roms including 31 Galaxians, 25 Street Fighters and 2 million Space Invader clones I have 2300 unique ROMS that work on Recalbox.
Honestly, give it a go after watching the video ( will post link if I can find it later)