I'm not sure I've digested your whole comment, but the basic idea is this: A "split" only means that the respective branches of the wave function cannot interf

I'm not sure I've digested your whole comment, but the basic idea is this: A "split" only means that the respective branches of the wave function cannot interfere with each other any longer. Then they will evolve completely separately from each other, and can be considered distinct. The only way you can get branches to interfere is if you have precise control over all particles involved in the entanglement, which is practically impossible for any macroscopic system. Long before you entangle with the cat system, the two branches have decohered. While technically there is still an enormous superposition there, for all practical purposes it is indistinguishable from being a classical system, with classically indeterminate branches. I should say that I'm not a fan of this explanation, possibly related to your points. Regardless of "practical purposes," QM does not allow me to say that there is a well-defined answer before it entangles with me (and that there is one afterward). I'm much more comfortable using the word "split" only there. But this skirts too close to solipsism for some, since "my world" (which I also know as "the world") only comes into being upon contact with me.