This is one of the most creative ideas I've heard for a while about Jem, and nice job picking the names! Of course they should have nicknames being in the entertainment world and Jem-world, and the only reason the don't already is because Hasbro didn't invent the characters, so yeah let's try to fix that.
Would be fun if we Jem fans could pick some short and Jem-sounding names that we would use to refer quickly to the characters. Hmm let's see what I can do, Craig Phillips, well he plays drums. I'd say Crash, as it starts off with the letters of his real name and refers to the most spectacular part of a drum set, the Crash cymbal! I'm not sure whether people are familiar with this word for drums, but I think it fits right in there with names like Clash and Riot. Only one letter differs from Clash though, but so does Riot and Rio.