I have never kept Krobia or Keyhole cichlids. A friend of mine has kept keyholes before and they did great in his community tank.
I currently have electric blue acaras in a semi-aggressive community and they are great for that…but I would not trust them with a smaller tetra like rummynose. My daughter also has an electric blue acara with various blackskirt tetra types (whiteskirt, black, and glofish color ones) and it does great there too. We both have Bristlenose plecos and the acaras are fine with them too.