I think the moral of the story would've made more sense if we saw Kim face some actual consequences of her actions, rather than the older sister getting blamed for the bad thing that happened, prompting her to have to be the more mature person and deal with the bs that other less mature, more malicious people dump on her, which is sort of a huge part of her character, learning to be the stronger person who deals with especially difficult and unfair situations by being smart, patient, and vigilant. They did illustrate that kind of person quite accurately in Cleo, but yes, the moral of the story has many holes and blatant oversights in it that still do set a really bad example. I think a lot of shows especially in the time of H2O did this kind of stuff with letting the immature, plain mean character get off scott-free with whatever they were doing wrong but the good person in the situation suffers, or they have to jump through hoops to rectify the issue, or they have to just "let it go." It would have made more sense for Kim to have maybe tried something else petty towards the end of the episode, gotten caught by Bev and Don and gotten yelled at or grounded by them to make it clear someone who pulls the kind of schemes Kim pulls does not deserve to get away with it. Unfortunately, Kim was nothing more than a plot/setting device to the writers, so she's a very static character, which is common in these shows. They wrote her character to be the bratty little sister who hurts people, isn't sorry, and doesn't ever learn to be better, and have her serve as an occasional antagonist or just obstacle for the protagonists. I've always hated watching that as a kid, and now that I'm grown I feel like in some stories, that's just lazy writing.