Hmm, about you two thoughts on Yasuka (and no spoiler because too damn lazy!)
For LowLevelLesser thoughts, ignoring it hoping it would work out was indeed a mistake of Yasuka but that was extremely trivial compared to her worst mistake: Believing Noriko's lie even though she knew the type of person her daughter really was. Even though it was Noriko's bitchiness that presented that path, it was ultimately Yasuka's decision to believe Noriko over MC that made them go down it. A parent's love for their child is a good thing but can easily lead to the worst possible outcome if not checked. I think both Yasuka learned that lesson, sadly one in not a good way which is probably what really broke her: Not her daughter's death but the realization that she played a part into that final outcome by spoiling her too much.
For HentaiGamerN00b, at first I completely rejected this idea but the more I think about it the more I'm leading towards the same conclusion. No matter how much she loved her daughter, knowing how she was there's no way she would totally believe Noriko unless her thoughts were less of "Believing my daughter" and more "Make a guy pay" which could have also played part to her breaking down after Noriko's death. Guilt towards MC.
Thoughts on Noriko's fate in current timeline:
I think regardless of what path you go down, she's pretty much in the clear from her death flag. The key things have pretty much been solved: Yasuka is no longer overworking, Yasuka has a much deeper bond with MC, MC is aware of the gang/yakuza existence, the rape lie from Noriko is less likely to happen and far less likely to be believed (even if he really does do it).
My thoughts in general:
Something tells me MC is not the only one who remembers the original timeline. The two who makes me suspect this is Yasuka and to an even greater degree, Sakuya. For Yasuka, this is just a feeling. She feels a lot more understanding towards him than even his past praising of her indicates which could be the guilt she feels or just me reading into it too much. Sakuya on the other hand, I feel like everything she does is to guide the MC towards her. Like, I just can't see what MC says happened to her in the original timeline happening in this one with one exception. She staged the whole thing with the jackass, it failed to get your attention, so she just went through with it and sadly it had a horrible result. Sakuya just feels too damn smart and scheming to be tricked like that. Then again, maybe she never really had feelings towards you until you tried to save her.... I don't know, but she's extremely sus. (and honestly, I love her for it!)