I like the dad's redemption mini arc, it's a complicated situation and I don't think there can be a truly all-win solution so it's a good enough outcome considering the things he's concerned about.
The new girl char has a kind of attitude problem is kinda a trope IMO, the "arrogant aggressive female char that later gets impressed/saved by MC and slowly becomes his fan and then softened up to be a damsel in distress". The bully bitchy attitude despite being a commoner might be due to a defensive-mechanism or inferiority complex (really fits the definition IMO), acting high and mighty not showing weakness/vulnerability like a thorn while diverting people's discrimination and resentment away from her to other vulnerable target(s). Realistic because such people really do exist, understandable sure but it's kinda overused and just not a fun personality (especially frequently found in gakuen/academy type of series), and I'm already kinda bored of this kind of character, ngl, but maybe it's just a popular female char trope for the Japanese shounen target market so it could be more of a business decision than a creative decision, can't say I'm mad about that but just kinda bored of it (I wanna see more big-boss sassy Bayonetta-style strong independent charismatic main female chars with BDE but that's not the ideal female waifu image that Japanese shounen market likes so...). Maybe for the same reason, when it's a female character of this trope, they are usually frenemy-rival who develop into tsundere female ally with potential romantic arcs, but when it's a male character it's usually the mob cannon-fodder status-abusive nobles or jealous adventurers that serve to give exp and levels for MC&co... so here's me hoping that there are more to this character as the story progresses and she'd surprise me.
As for the "pretending unaware of the romantic interest" situation, I think there might be a betrayal or MC hasn't moved on from losing a loved one or something while having other priorities + she's too young for his mental age that she's just seen like a sister/daughter/student by him... which I totally appreciate that much more. I can't imagine myself or most average people would find young teenagers or kids attractive in that way if they were to reincarnate/transmigrate and relive as a kid/teenager with an adult mind (when setting-wise the mental age is not affected/restricted by physical age)... Cute and precious like a sister/daughter and want to protecc, sure, but romantic interest? no way, not for non-pedo people let's be real. It's not even like the past kid version of the future wife/husband you had in the previous life or from the future that you already had a connection with before the current life/timeline. Him acting dumb and unaware of the interest was probably an indirect way of not embarrassing her or hurting her feelings and don't wanna lead her on too hopefully she'd give up after getting "sis-zoned or whatever -zoned that is".
Why do I overanalyze things so much...