EL is not a ROM manager either. I just coded a very simple audit feature so I can update my ROMs inside EL, but mostly to eliminate merged sets, which I hate. I find current ROM managers too difficult to use.
>> ...don't even know if i can call it a "front end" frontend = user interface (according to Wikipedia)
Don't be afraid to use EL features as a base for your frontend... even make them better in FFE. EL is free and open source.