It's probably no coincidence that Asahi would emerge in the story at the same time as Yotsuyu herself returns to the story. It seems they definitely have a story they want to tell in regards to whatever Yotsuyu's family did or did not do. Not to mention Gosetsu, even during Stormblood MSQ, seem to know more about Yotsuyu then anyone else in the plot and the fact that he did save her seems to suggest there is possible more to the situation that hasn't been established especially giving the dialogue in the trailer about 'where do sins lie'. I doubt it will be enough to make Yotsuyu redeemable but it might be enough to provide a little bit of empathy or understand to what led up to who she was.

She doesn't need redemption or forgiveness, but some understanding would go a long way with the character.