so as many have thought, the soul in beatrice is raeliana's old soul
and our current raeliana is beatrice's old soul (which i find to be such a beautiful and perfect plot twist, for noah to still fall in love with her, i'm still not over how perfect this is)
also,the thing about reincarnation and her being a korean person in the future, so that korean person's soul is our current raeliana's reincarnation
but for some weird reason she came back to "princesses and kings" time
so when she goes back to the future she forgets everything but noah s reincarnation looks for her and finds her again