I've read that happening, but does their gender really change?The auratus is turning male. He will get a dark brown body color with narrow yellow/white stripes. He will become more aggressive when he changes.
There is a troublesome mix of fish in that tank.
I have read of dominant females coloring up like males when there are no males in the tank, and pairing up with the sub dominant female, but the eggs that were laid of course weren't fertile.The gender does not change, the males just color up at maturity. As far as trouble, you don't get much with a bunch of juvenile fish, which you currently have. When they start to mature sexually, all bets are off. Males will become very territorial and start fighting to determine who gets the best spot. Females will be harrassed if you don't have enough for each species. This is a common problem when beginners try to start a Malawian tank. They think things are fine because the youingsters are getting along. Usually somewhere between a year and a half to two years is what it takes for most Mbuna to mature.
The juveniles in the wild spend their time trying to avoid being eaten. The adult males spend their time trying to attract a mate and defending a territory for doing so. Females shoal together and feed, and when the mood hits her, she will go find the most dominant male and spawn with him. Then she finds a quiet spot to brood her eggs/young. In a small tank like a 55, it is hard for them to do any of these things.