Currently the default value for the parameter in set z index is 0, but this doesn’t work how you’d expect it (clones at z index 0 cover up a different object at z index 2) so it would make more sense for the default to be something else, like 1.
I’ve noticed that as well. I started putting the block in basically every object
To be honest, I have never used Z index yet, but I think I understand what you mean and it makes sense to me.
Another solution would be to support negative Z indexes.