Bichirs aren't as aggressive as they look, especially Senegals. It would definitely fit in with the oddities of Knives and Elephant Nose, but I would worry about the aggression of African Cichlids. I'm not really an African Cichlid guy, so I can't really say how they would fair with them since I know their aggression can vary from species to species (like most other fish).
I actually have my group of Senegal with 1 male African Peacock Cichlid but would not try this combination until you learn behavior of Cichlids. Absolutely wouldn't mix with Mbuna a smaller but more aggressive African Cichlid specie.
The Brown African Knife or African Elephant nose should be fine.
I had a sen in a tank of cichlids. No real issues that I saw. I mostly had mbuna species even had a breeding pair of kennyi and brichardi cichlids. The male kennyi was a jerk, my wife brought home a really nice peacock male that the kennyi killed almost instantly. Other then that he was just a jerk to everyone including me during maintance and really any time I was near the tank. I grabbed him every time I did maintance didnt phase him one bit. I know alot of the babies disappeared and I assumed the other cichlids, but now knowing what I know about polys it was probably as much or more the sen. But anyway never saw them really pay attention to the sen.
I did see a large poly cant remember the type may have been an endli missing both eyes at the lfs. They said he was attacked by the cichilids that he was housed with at the persons house and since they are a huge pet store and have two vets on staff he was surrendered to them. One of the staff eventually took him home.
Like others have said you'll have to know your cichlids.