It feels like they only left MC's family's circumstances (as in comparison to WN, according to comments) in manga to have a justification for MC to connect with Kazemiya. Other than several alarming interactions in the beginning, it really feels like MC was just being overly sensitive.
As for Kazemiya, i'm not really put off by her trying to make up with her mother, nor by the fact that it didn't really went well, but it all felt irritatingly naive, as if Kazemiya was planning to just forgive her for all the abuse, without getting any apology whatsoever. Heck, Kazemiya even apologized herself for not understanding how hard it was for her to be a single mother of two. I mean, i get that it ain't a walk in the park, and it might be better for the family when children understand that, but not knowing that is not something they gotta apologize for.