Basically, what I'm trying to say that it's a waste of time to debate what St. Thomas taught or, rather, in this case, believed, since it doesn't matter that much for this debate.  So move along.

It is only natural that if someone incorrectly claims that St. Thomas taught the earth is flat, then people who know this to be false will object. I agree that it has little relevance to determining the shape of the earth, but you can't expect people to let falsehoods go unchallenged. 

While it might have been considered hubris for him to interject his personal opinions on matters of controversy ,,,

Not in matters of "controversy", but in any matters at all, given that this is a "Commentary", the entire purpose of which was to explain Aristotle's thinking rather than as platform to present your own thoughts.  You misunderstand the very nature of a "Commentary".

St. Thomas was not using his commentary as a platform for his own thoughts, nor am I claiming that he was.  He referred to spherical earth as the truth because this was the consensus of all educated Catholics at this time.  They all (including St. Thomas) believed it to be objectively true that the earth is a sphere.  The fact that we can deduce what St. Thomas believed from this does not mean he was using the commentary as a platform.

You assume that ever-increasing scientific knowledge wouldn't prove Flat Earth more and more. I disagree. I think the more we experiment and grow in knowledge, the more flat earth is proven, and any "globe" fantasies are destroyed.

For example, Evolution. 70 years ago, evolution was more believable, BECAUSE science was more primitive. We knew much less about the inside of a cell, DNA, etc. With increasing knowledge, the lie of evolution became LESS tenable.

Ditto for the globe. Maybe during an age of general ignorance about physical science (let's face it, they didn't have computers) one could believe the earth is a globe. But today, with airplanes, radio, etc. the very operation and existence of these technologies proves the earth can't be a spinning globe. Also Nikon zoom cameras. The "ancients" cited ships going "over the horizon" as evidence for a globe earth. Today we find that a hilarious joke. We can "pull back" every one of those ships that "went over the curve" simply by zooming in.

I could give dozens of other examples.

Where did St. Thomas refer to spherical earth as truth?  What Catholics believed spherical earth to be a sphere? 

.

It's on the first page or so of the Summa:

Objection 2: Further, different sciences are different habits. But the same scientific truth belongs to different sciences: thus both the physicist and the astronomer prove the earth to be round, as stated in Phys. ii, text. 17.

People have objected that this is simply an abstract statement. But he says the same *scientific truth* is *proved*. He wouldn't describe it as a scientific truth if he didn't think it was one.

 the fact he compares the earth to a cathedral.

Where did he compare the earth to a cathedral and what exactly did he say?

Where did he compare the earth to a cathedral and what exactly did he say?

I don’t have it anymore but I did have it from another forum and now it’s been deleted it was the EARTH IS NOT A GLOBE ACCORDING TO CATHOLIC TEACHING on flatearthtrads