I can't comment on unreleased things and extra content is often more comedic, but I can kind of see the rest of that - Kurumi doesn't have many people she's actually close with.The comedy is in the volume bonuses and twitter artworks that haven't been released here yet. And even those are deeper in a way, since they foreshadow certain things.
As for Kurumi, she's not really respected at school by many people. The teacher gives her fake praise to make her do his work for him. While her club mates slack off expecting her to do extra work to make up for them. And during the school assembly, many of the students gave the impression of not caring about her. Even outside of Isanuma's clique and Naoi, there were girls looking bored and in particular one looking at her nails. The desk incident could just make them more comfortable revealing how they don't like her and start spreading rumors about her. Though that won't be too relevant for awhile, given summer break is about to start.
Kokoro could be in for a rude awakening too. Her parents took notice of her off behavior and assume it has to do with the school. If they contact the school after Kurumi does something, Kokoro could be banned from talking to her. Or they could force her to switch schools to get away from bad-influence Kurumi.
Naoi really has nowhere to go but up from here since she already reached rock bottom.
I think though it would make sense everyone would have detractors since students tend to congregate in groups of like minded people, not necessarily showing she is disliked in general. Not everyone will care about school speeches etc naturally and some people will feel insecure around someone who appears to always have everything together and do things by the book, but that doesn't mean she isn't generally respected. I do remember there being certain people who are outgroup to essentially everyone (or do I mean being the certain people, but let's not talk about that), essentially the minority that lets the majority be a majority, but I can't remember anyone post elementary school being loved by everyone.
Maybe it would be best to say a good reputation with few detractors, but also few allies who would stand up for her? The girl who is clearly romantically interested in the teacher is kind of biased, as these things go, plus is maybe actually involved with him given the type of story this is.