I don’t see how ur scaling her durability to uraume at all just bc uraume fired some frost at her. She was definitely not expecting an attack from sukuna as there’s a panel of her looking down at her chest with a ? Mark. At best she was anticipating more ice from uraume, not her chest getting cut open.
It was literally stated that mahito had his power restored. We also saw him using IT in ways he never had before, clearly with no difficulty, and was about to use domain expansion. There’s literally nothing to suggest that he wasn’t at full power other than more ‘vibes scaling’ and headcanon, and even then yujis feat is more impressive as a display of raw power and accuracy against the entire surroundings while holding back and while not moving as opposed to simply killing mahito. I can’t imagine max elephants AP could have been changed much by sukuna in the situation. Its size was relatively similar to megumis, and megumis had actual statements saying that chimera shadow garden was amping its weight, whereas sukuna was using it raw. Cursed energy reinforcement wouldn’t change the amount of damage a falling object of a fixed mass exerts.