I would stay with Full LB Yshtola, because you already have 2 other good URs, at one time or another Frederika will come for you.
Another point is that you will no longer be able to get Yshtola Shards, and, it is very traumatic to try to level more than 2 URs because you will not have any more rainbow resources, MR units are also powerful, think about it.
I had rerolled like more than 100 times.
The best result i got was
I satisfied with it. But have doubt that, should i keep this and let go of my Medeina & Ayaka account?
Moreover, I had played Frederika, its much fun than Medeina. Its challenging. Idk.
Then I think I should safe my visiore to pull the double gun girl. Hehe.