Well I think I have managed to solve it in another way.
I’ve downloaded a seperate FB Neo romset, which contained CPS1, CPS2, CPS3, Cave, Neo Geo etc. All in all +500 roms.
Imported the FBN Roms in LB. So now I have all the +500 games working in Retroarch as a seperate Final Burn Neo platform in LB.
This means I now have double roms - versions working in FBN platform and same games in the Arcade platform, which is not working.
What is the easiest way deleting these roms which are not working ?
These roms are also figuring under the Capcom Classics playlists..