My extremely limited, incomplete, and non-mathy understanding of QM makes me suspicious of your explanation because it talks about things like macroscopic measurements affecting the fundamental level of reality, and about fundamental events only happening sometimes in special circumstances.

World-splitting in MWI is not a fundamental event. "Worlds" themselves aren't fundamental objects in the theory. They are imprecisely defined macroscopic entities that emerge from decoherence. So nothing I say involves macroscopic processes affecting the fundamental level of reality.

ETA: Perhaps you're thrown off by my use of the word "measurement" because it suggests something vaguely Copenhagish. All I mean by a measurement-type interaction is an interaction between the system and its environment that leads to einselection.