Semver was enough for me to resolve very simply a scenario above that was presented as some kind of unsurmountable nightmare. So I think Semver is just fine. It's an example of a simple, well designed abstraction. Having "more bits" is not a virtue here.

I could have some comments on your "overlapping responsibilities" as well, but your description is too abstract and vague to address, so I'm pass on that. But you literally described the concept of library at one point. There's nothing overlapping about it.