"I just need to visualize the illness vanishing"
What a fascinating statement. She doesn't even know what the illness is, and yet she can picture it vanish, not to mention have the ability to "picture" the body of a healthy, middle aged woman.
I'm not really shocked about how quickly it was resolved, isekai-trash be isekai-trash, but I am surprised that the author cared so little, that there was no even "I see a black clump, let's get rid of that!" -- or "let's accelerate her healing factor and hope for the best!" -- or even: "let's imagine Saint Maria and hope baby Jesus will heal her!"
Nope. Just, poof.
Now that's an impressive level of laziness. I do not recall the last time I saw an author give so little fucks. I still do not understand why these shitty WNs get manga and anime adaptations, who'd even buy this piece of shit.