The sixth prince, who had been executed in the kingdom after being betrayed by the trusted saint, was reincarnated and, in order to seek revenge, became engaged once again to the neighboring kingdom's “Guillotine Princess.” As a result, he

Sigh, it seems you, just like the author wants to have your cake and eat it too. Either this world is so discriminatory that duds can't even get justice. Which begs the question again, why MC or any other duds would go to college there. Or it's not that bad, that MC feels safe enough to go to a superhero school.
Remember this is a futuristic world with recordings. We know the kids would have gotten in trouble because they killed them in order to silence them. The fact is the villains, even though they have backing, they do not have enough backing to simply murder people. Again, let me put this in a way you might understand. A racist in N*z* Germany is not going to hide their antisemitism. In their world, it's a good not a bad. A Jewish girl going out trying to get justice, they'd just be laughed at and disappeared. While here, in this world, they kill the people to stop them from revealing their secrets. Why? Because there would be negative consequences.

Lavender stared critically at the vortex off the stern, it was spinning a bit faster than usual, but the pattern was steady with no dangerous fluctuations, so she just carefully skirted the magic circle chalked on the deck. Leonora's hands were resting on the stern rail, but it was no white knuckled death grip, and the rest of Leonora's body language said that she had things under control.