Are you seriously proposing that *my* use of ambiguous _language_ splits the universe? This is unbelievable. I understand how incoherency would split the universe, but how can ambiguous language do that?

It doesn't split the universe; your language doesn't have any effect on the world; as I said, it means that you have to consider a larger set of microstates, which means a larger set of outcomes. The better specified the initial conditions are, the better you can predict.

How about false information -- if my bank tells me that my paycheck came in, is there an alternate world where my paycheck in fact DIDN'T come in? .... There may be a world in which my paycheck didn't actually come in to my bank -- but the explanation for that lack is NOT "because I just imagined it", or "because it's the negation of something that did happen"; rather, it's because of some specific quantum decoherence which could eventually result EITHER in my paycheck arriving or NOT arriving.

Yes, there is such a world. Yes, there is a causal explanation for it, based on some decoherent split that occurred a long time ago and caused a neurotransmitter to jump one way (or the other) in some secretary's brain, causing ver to get distracted (or not), and to forget to note one deposit (or not). All asymmetry in the universe results from quantum 'randomness' at some point, even if it was back at the Big Bang, so any physically possible world is in the wavefunction somewhere (as are physically impossible but logically possible worlds in simulations).

So, in a sense, I was wrong to affirm "Does every event with two possible/plausible outcomes result in two distinct worlds?", because only subjectively does the event itself split the world; the objective split might have occurred billions of years ago. But, yes, every outcome is real in some world.