Imagine for a moment that Sunburst knows far more about magic than you think. So much more, that the princesses keep his knowledge compartmentalized using Shadowlock as his handler. If Sunburst had access to all the forbidden and arcane wisdom he has acquired he’d go insane and if he could perform even a little of the functional magic he’s allowed to know, he’d be a real danger to everyone, as his special talent is inspiration. For that reason he is under hypnotic suggestion living under a facade as a magic school flunkee. The reality is that he’s a sleeper agent.  
When the kingdom is in dire need, Shadowlock is under orders to execute the Deep Magic Protocols to unlock facets of Sunburst memories and spell casting capabilities in order to combat cosmic horrors and incomprehensible truths that loom beyond the typical magical awareness. Or something like that.
 
I feel like Shadowlock and Sunburst make an interesting duo. One buries truths while the other discovers them. Sunburst’s knowledge but lack of magic in the show has always trouble me. It just doesn’t add up so I’m always looking for an explanation. Shadowlock on the other hand has this MEN IN BLACK feel. So I got this idea of a MKUltra experiment that utilizes both their talents in way to overcome the normal limits of cognition and make Sunburst the closest thing to a living Akashic record while Shadowlock is the index.  
I’ve also played with the idea that Sunburst’s flashes of inspiration aren’t flashes at all, and that ShadowLock is just flipping a switch on and off from afar when needed. Without ShadowLock inhibiting him Sunburst would be a raving lunatic writing on the wall, encumbered by blinding insights.