I think it's interesting and problematic to speak of transubstantiation being about "what happens physically." I wouldn't describe the change as a physical change (except in some of the more spectacular miracles). Nothing changes physically.
At least as I use the word, that would be about what measurable and analyzable changes happen to the "elements". But as I understand the doctrine it is pretty much a declaration that nothing perceptible to sense, even to senses augmented and refined by instrumentation, happens.
So then the question is, "What is changed?" And the answer is "The what-it-is is changed," as distinct from what-it-looks-like or what-it-is-made of or things of that kind.
And I don't think that reduces the sheer mystery of the thing. It just is an effort to say precisely something about the mystery, to assert the mystery less vaguely.
If one is willing to embrace the doctrine of the transcendent creator becoming a man, on what basis can one deny the creator becoming ANYTHING in his creation?
The mentality is like Darwinism turned upside down; once accepted there is literally nothing its devotees think it can't accomplish, including that which is physically impossible!