Yes, the witch scene was clearly animated (and presumably finished, apart from probably Nura/Meemee's part) as we see it there, and then reworked mostly in editing to include Tack/Yumyum instead.

Very strange original punchline to it. Note that the witch doesn't blow herself up either.

So, only something like two Williams-animated changes from the original then. We do see the witch pull Tack to the ground, which would have been reanimated from a shot of her pulling herself up onto the Beast, and we see her blow herself up (and meet the Thief).

The rest only filled in by Calvert really.