Yk... when it comes down to it, the only opinion that really matters is Eri's. I doubt she'll be forgetting anything.
I'm starting to see a pattern where a care taker of Eri's talks to Chisaki in place of her. As if they know exactly how she feels and what she wants to see from him.
I've had this happen to me and it's so infuriating (I was the same age as Eri, and now that I'm older I really wish the adults in my life would've only separated me from the problem, not speak to the problem as if they knew how adult me was going feel. I've had to undo so much misinformation, it's such a pain). Pops and Deku can think what they want, but what they should've said was that Chisaki's forgiveness was in the hands of Eri when she's mature enough and ready to make her decisions about how she feels.
You can't possibly guess how she'll deal with Kai. Doesn't matter how you'd feel in her situation, you aren't her. There are so many ways Eri might go about it.
A prime example are the Todorokis. Every one of Endeavor's children had a different way of dealing with their relationship with him. Natsuo pushing him completely out of his life, Toya going mad, Fuyumi trying to keep the peace, and Shoto continuing the path Enji put him on, not for Enji's sake but for his own.
I really hope Deku or Pops don't speak ill about Kai infront of Eri. All they should do if she brings up the topic of Kai is to listen, if she's confused on how to feel, give her time. Tell her it takes time and maturity to make those type of revelations. It's ok to hate him, it's ok to never want to see him again, and that it's just as ok to want to talk to him, to feel indifferent, nothing, or forgiving toward him.
The best way to teach a child/teen to be free thinking, to learn about themselves and make their own decisions in the future is to not put emotions in their head. As a parent or guardian in a child's life, your job is to show. Show them all the points in life. So when their older they can form their own opinions and life philosophies. They may not be that same as yours and that's ok. A child is a whole different human, they are going to be different.
Anyway, I'm babbling nonsense. Pops doesn't even know Eri, and Deku can't read her mind. Her intentions will never be known. And maybe she never does think of Kai again, and I'm ok with that.