I don't remember that, but I know that Spongy can usually resist more damage thanks to him being malleable. If Anna's starry sky power is the same as what Leafy's is regarded to be as, then since she doesn't have the same body as Spongy, she probably won't resist Leafy's knives. Keep in mind, that Leafy's knife throwing is danmaku, so they aren't easy to dodge.
It was never really established where the location of the Leafy Recovery Center is. The original post states that Leafy has access to all of her equipment, but her Recovery Center is destroyed at the point in the timeline this battle takes place in, after BFB when Firey and Leafy went away on a boat. I assumed the Recovery Center is just inexplicably back in a way that's relevant to this battle, somewhere out of the way, maybe behind a tree or something like that. It may take a few resets for Anna to get all the information she needs, but since Leafy will have the same plan of attack every time, I think that Anna would eventually simply know where the Recovery Center is, see right through Leafy's attacks, destroy the Recovery Center, and then burn Leafy. I don't know exactly how Anna's fear manipulation and empathic manipulation work, nor if she would use it, but her having those abilities to potentially weaken Leafy's mindset is another reason why I think Anna would win.