People seem to care a lot about this whole thing with the mother and sister and how they need to repent and all that, but to me, it feels like just an obligatory setting thing. They had to get it out of the way at some point, but I don't think it's all that relevant.
What these recent chapters are actually lacking is character interaction. The concert felt incredibly dull because, unlike the confession in chapter 19, it was basically just the characters singing and having the most generic thoughts imaginable, we've come this far together yadda yadda. Not even memories of their emotional moments together, not even exchanging a glance while performing, just bubbles with lyrics. Almost like the author forgot it's supposed to be a romance manga.