You'd need to test against what kind of vase you hit. Either via the vase object's name, or a component attached to it or it's tag... Then do +=1 or -=1 depending on which.
It seems sily to have the roof completely uniquely unwrapped, what type of game is this for? I would just have 1/3rd or 1/4th of the roof unwrapped and just tile it.
Hi, high-poly shouldn't matter if the UVs of the mirrored parts are offset. It will bake for UVs inside 0-1 space, mirrored parts with UVs offset by 1 will reuse the baked information: high-poly details are mirrored.