I have confirmed level-end warping also resets stars.
Viewing post in Grapplehook Midpoint Teleport Killer comments
I realized the hint in the hints didn’t refer to what I thought it did, so it’s possible now, but the game explicitly tells me this isn’t necessary so I really wanna know how else it could be possible. There’s definitely no way to grapple through the solid ball wall without the unneeded spell, so I must be missing something else