Dear Ian,
"Universal beables may not be knowable, but local ones, as in those bounded within a particular region of space-time, might." I wonder if the particular regions you mention are those that agents can think of ? Because then these regions can be infinite. I agree that "universal" beables are not knowable when universal means beyond konowable.
"At the very least, it suggests that Maxwell's electromagnetic theory is incomplete". Isn't EVERY Theory incomplete ? Human intelligence is only a very short time trying to find the HOW and WHY of our existence, let's hope for the future developments (if any)....
"I may awake tomorrow to find that I am actually a Buddhist monk living in a monastery in the Himalaya and that my life as a physicist was nothing but a dream." Indeed in the here and (until) now you are a physicist. This is the reality Loop you are conscious of right (until) now. In another Loop the probability of being the Buddhist monk is available andthe monk dreams being a physicist.(what is better ?)
I think Fields are experienced through technical addings to our senses, they are transformed to comprehensible information, so they are "interpretations"..of emergent agents (for humanity with 5 senses) in an emergent reality.
'universe of our experience' the world around us reaches us as on the surface of Subjective Simultaneity Spheres around us , the result of these experiences are the models to explain our experiences.
"Everett-De Witt multiverse, for example, includes an infinite number of universes. This definition is simply too vague to qualify as a beable for any realistic theory." I can fully agree with that so I devellopped another perception that could also explain the problems as are solved by MWI. Therefore I would be grateful if you could read my essay "Foundational Quantum Reality Loops and leave a comment and/or rating on it.
"But the wavefunction in the Wheeler-DeWitt equation suffers from no such defect since it is said to be 'timeless', i.e. it simply 'is'.". The simply "IS" is more difficult as we think (I think). Timeless can also mean "eternal" or not present in the time restriction so outside of our "reality" (is that the same as "non-existing") a "notable"...
It was a pleasure reading your contribution, it was helpful for my own quest.
Best regards
Wilhelmus de Wilde