Well that was a bit silly, if they were all 5yo's then bedwetting would may make sense. But if they genuinely wanted to damage her reputation and shake her spirit then they should be making people question her competency to rule, like interfering with the chain of command, something they could easily do and could cause serious damage to the country.
It's just a start, a chink in the armor of someone who not only wants to be a perfectionist, but wants to be seen by everyone else as a perfect individual at all times. Being so relaxed or lazy that you wet the bed in your sleep
is innocuous, which is why it's so devious: nobody would suspect foul play, immediately fabricating "a lie to cover up the truth" (when it's really "a lie that covers up another lie.") The very fact that she's covering it up gets people to talk, and ruins her powerbase.
Not to mention, her faction is already less popular than the twin pig princes'; she can't afford to squander what little support she has.
Even so, this wasn't the big plan to destabilize Camilla's faction, since Kento's not quite ready to do that until he can secure the rest of the students, but instead just a bit of schadenfreude on someone who
really deserved it.
tl;dr it's just a prank, bro. Until it isn't.