The regal angels they’ve captive bred are actually Pygoplites diacanthus flavescens. So they will have the yellow belly but are also the brightest of the three colours.
As for the OP’s question. These are supposed to be trained onto eating a variety of prepared foods, pellets, frozen ect… however, pellets alone cannot suffice as a diet for any fish (Even Clownfish, Gobies, Blennies ect) so it’s best to go for the varied or frozen and herbivorous diet (Personally if I have a tunicate or sponge suitable tank then I would propagate that for food for the Angel as it is their natural diet).
As for how often you should feed, since the angels you’re seeing are the harder species, yes they need 3 times a day feeding unless you have plenty of grazing areas throughout the day.