The story has at least two occasions where someone does something that is fully within their character, but the result is a poor (or at least unsatisfying) narrative.
Yume's death: based on all the Hoshino flashbacks we get to see, she definitely is the kind of person to get herself killed by trying to walk across a desert without proper planning/equipment. However it's built up as such a mystery, by comparison the reveal feels like a whimper even with the genuine emotional weight through Hoshino's grief and guilt.
Hoshino insisting she must go solo: there's a genuine reason cited, she wants to take all the blame/responsibility for anything that happens, and spare rest of the Abydos students from the trouble. Problem: this is basically a repeat of her character arc in original two Chapters of Volume One. Ayane even explicitly points out to Hoshino that she's doing the exact same thing again. One one hand, this could tie the whole Volume One C1-3 together with a theme/arc about how trusting people, even your close friends, isn't easy. As in, Hoshino has no problem jumping into the fray and trusting that rest of the Foreclosure Task Force has her back. But when they say they're willing to get entangled in a major conspiracy/legal dispute, Hoshino has hard time believing they really A) know what they're signing up for B) are ready to take on all the long-term consequences. This could've been interesting conflict if executed well, but it ends up boiling down to Hoshino fighting rest of Abydos 1v4 and winning twice (at least.) This can result in feeling like they're just punching bags for Hoshino. (A trope called "Worf Effect" - TNG writers made a habit of having various monsters/villains of the week establish themselves by whooping the eponymous Tactical Officer, greatly tarnishing his intended badass stature.)