Cories are not clean-up and would not do well with Mbuna. The only suitable tankmates for Mbuna cichlids are other Mbuna. The electric yellow is not a social fish as is keeping with the Mbuna profile. Meaning that it isn't an absolute, but not likely workable for other tankmates. Staying with other Africans of the Mbuna species is your best hope. They are very territorial and often like multiple shelters. Having other Mbuna is no guarantee of compatibility.
You mention something about "piles" but leave it hanging so what you mean is not clear. Having kept the Electric yellow cichlid for many years still leaves me scratching my head trying to find suitable tankmates for them at times. suggested compatible fish: Auratus, Cobalt Blue Zebra, Electric Blue Ahli, Electric Blue Johanni, Featherfin Squeaker, Upsidedown Catfish, Zebra Cichlid,
Based experience, I would personally not consider the Auratus as they are also known to be temperamental as well.