or even individual positions of a structure

This would be the only reasonable way to support conditions regarding structures (and would only work for worlds generated with Unbreakables present)

This feature would be amazing if you could pull it off! There is a mod called Structures Tweaker that exists, but the implementation isn't as sophisticated as this mod. I like the way that this mod doesn't show the destruction animation when breaking blocks, whereas the other mod does. It confuses players into thinking there are lag issues as it doesn't even display a message.

Nothing against the other dev, it's a great mod and the other features will definitely still get used by me, but the block break protection features would be much nicer in your mod.