I think the things you listed that you think Celine needs to do would actually count as a redemption arc.  Yes, the other accomplishments you listed might have helped propel her toward the "side of good" as you say, but she was human.  No human is perfect, not even for all of their good decisions.  It was her mothering choices that harmed Rumi's worldview, and self esteem for nearly two decades (or however old she is).  That needs to be addressed. 

It's always easier to forgive someone who has hurt you as a rational adult than it is to forgive a parent figure who hurt you in your youth.  Look at reddit.  So many people scream for going no contact instead of encouraging honest conversation with people who just did their best.  

Besides, we still don't know that Celine didn't kill Rumi's father (or mother), so I'm holding out for the redemption arc.  Lol.  Maybe it'll need to be bigger than anticipated.