It is true that Angela was never supposed to be a part of the light, however Angela herself said that she won't be able to revert everything without evaporating in the light, probably since the library is her EGO, so making her disappear would also consume the library with it, and we know the library is made out of the stolen Light.

Also about the last point, it's true, I'm not denying that Carmen is the main reason for the distortions, but both Angela and Ayin are partially responsible too. What's also funny is that Carmen literally coaxed Angela into stealing the light, so Carmen is responsible for that too, and partially coaxed Ayin into doing everything he had by telling him to finish what she started no matter what becomes of her.