Are we just disagreeing about the meaning of "understand" or something? Are you using the word "understanding" in an unusual way, such that there is no such thing as non-mathematical understanding?

No. Some things can be understood without mathematics, and some can't. I'm just claiming that QM and relativity (including the basic intuitive understanding of these fields) fall into the latter category, and by extension also various fields of modern physics that have them as prerequisites.

Also, at one point you seem to say that I can't have evidence about whether Copenhagen is correct or incorrect without understanding all the equations involved? That seems too obviously false; I assume I'm misunderstanding you?

I have no idea what you mean by "all the equations involved"; I certainly never mentioned any such thing. There are many different ways in which Copenhagen might be formulated, which may involve different mathematical concepts and equations used to express them -- but any formulation that rises above fuzzy and obscurantist fake-explanation talk must necessarily have a mathematical basis. I mean, if you're going to talk about "collapse of the wave function," you'd better have a solid understanding of what a "wave function" is and what exactly it collapses into.