Another factor to consider is that relativity showed that whether two events at different locations are simultaneous depends on the observer's reference frame.

Another factor to consider is that relativity showed that whether two events at different locations are simultaneous depends on the observer's reference frame. See (https://en.wikipedia.org/wiki/Relativity_of_simultaneity https://en.wikipedia.org/wiki/Relativity_of_simultaneity). So you can't even say which measurement of the state is the one that collapses the waveform. Observers in different reference frames would disagree.