The romset is a tested and complete one coming from a reliable source and to make sure I checked it with clrmamepro.
It's a 7zipped merged set (which means that there's only one 7z archive per game containing both the main rom and the clones' rom) which is supported by MAME itself AFAIK.
I've made the database file myself with ROMlister following the guide on this forum, using latest MAME XML, latest catver.ini from ProgettoEMMA and nplayer.ini (or whatever that's called).
Everything works fine, really, all games correctly show up and stuff but there are no clones shown, even if I light up the button