Has Cyphotilapia gibberosa been accepted as a species?
Scientific names dont necessarily represent biological species. In the case of Cyphotilapia, nobody checks the species status of C. frontosa and C. gibberosa based on the biological species concept and that is the most popular species concept now.
However, I think different scientific names should be used for these fishes. It will be better practically, for example, as an estimation of biodiversity of Tanganyika cichlid fish.
What about the six and seven-banded forms of C. frontosa?
Six and seven-banded morphs are separated by number of vertical bands on the body side of C. frontosa. I could not find any morphological differences between these morphs.
According to the standard of taxonomy of Lake Tanganyika cichlids, these forms are not different species, but are just colour variations within a single species.
However, of course, further research, including genetic experiments and mating experiments, are required to know whether these are different "biological species"