This is just a straw man.
The Church doesn’t define any kind of reality. The Church defines true propositions about that reality which have been revealed by God, and what constitutes a “matter of faith” is not limited to things spiritual or only “essential to our salvation” - that’s Modernist tripe of the kind that makes a nonsensical distinction between something being “theologically true” and otherwise! - no, it includes facts concerning human history, the nature of man, and cosmology. If the Bible states that the dimensions of Solomon’s Temple were x,y and z, the the Church has the power and authority to infallibly declare in this matter.
“Objective observation”, by the way, is a contradiction in terms, and the notion that a “physical reality” - by which really meant a theoretical model abstracted from sense experience, thus based not only upon uncertain data but upon projecting conceptual fantasies into that data in order to postulate the existence of a world lying behind the content of sense experience - the notion that this process - of the blind grasping in the dark for a cat that might not exist at all - could take precedence over divine assurance of truth is preposterous.
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What you have said here is partially true, and partially false.
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The Church doesn't define reality that we can verify by objective observation.
Things like the depth of the sea, or the limits of the sun's northern or southern declination each year, for example.
But the Church DOES define reality in
spiritual matters, such as the Assumption of Our Lady body and soul into heaven.
So to say
"the Church doesn't define any kind of reality" is incorrect.
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The dimensions of Solomon's temple is not something that can be verified because the temple no longer exists.
If the temple were still existing, the Church wouldn't declare that its dimensions are other than what can be observed.
Objective observation is its own reality, by the way.
There are those who deny the evidence of direct personal eyewitness.
Thanks to Hegel, Locke, Hume, Comte, Kant, Marx, Nietzsche and their ilk, we have no shortage of deniers of observation.
I hope that's not what is infecting your perception!
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Regarding the flat-earthers' claim that the sun is close to earth, a few thousand miles, here are some observations:
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The sun would be further away at sunrise, closer at high noon, and again further away at sunset.
Therefore the sun would appear smaller at sunrise and sunset than it does at noon.
But that is not what we see, in fact.
Flat-earthers go so far as to FALSIFY videos of the sun by not using a solar filter, which makes the sun appear larger than it is.
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