I'm sure their shyness is because they are the only fish in the tank, or they cannot see the others. Adding few dithers, such as guppies, might bring them out.
My knowledge of other Tanganyikan species is limited, but hopefully it will help you in choosing tankmates.
You could go for a pair of Julidochromis transcriptus, or a colony of J. ornatus, which ever you prefer (just try not to mix julie species as they could produc hybrid offspring).
Neolamprologus leleupi and N. brichardi would probably go well with compricisseps. The larger shell-dwelling species..