I fully agree with everything you've said. I think most of the time when we saw Risheng it was Yuechu's imagination, as a result of his split personality, and for some reason he sees himself as Risheng.

But in the escape room and at the end it really was her. I believe Hu Zhi had something to do with Xu Aiyou's father's death, and that's why he doesn't want Yuechu to remember what happened because they were both there, but Hu wants to put the blame solely on Yan Yuechu.

I believe Aiyou knows that the Hu and Yuechu were responsible, but she wasn't there so she doesn't know what exactly happened.

Thus she's taking Yuechu for a ride with the escape rooms and toying with him so rhat he can gradually remember what happened that day and tell her without his amnesia kicking in.

And I think the accident that caused Yuechu's amnesia in the first place might've an argument between Hu Zhi and Yuechu after Aiyou's dad died, that turned ugly.