I was not talking about the FE's on this forum. I am talking about the people behind this movement. I worded it wrong. I refer to the people on this forum as Dogmatic Flatearthists because they have been duped into thinking it's a Dogma.
The FE's behind this movement are enemies of the faith. They know the world will look at this opinion as "crazy". The devil knows that to introduce this as being a doctrine, not only will it discredit the faith but it has the added bonus of a schism. There is no doubt that a lot of people on this forum believe this is necessary and that others who believe in GE have no hope of salvation unless they convert to FE, whether they say it like that or not.

Fair enough. I just didn't want those undecided who may be reading to be persuaded by the FE movement's exaggeration of FE belief among the Fathers.
I tend to agree with these opinions, since it hasn't been decided by the Church.

St. Augustine, The literal meaning of Genesis: "It is also frequently asked what our belief must be about the form and shape of heaven according to Sacred Scripture. Many scholars engage in lengthy discussions on these matters, but the sacred writers with their deeper wisdom have omitted them. Such subjects are of no profit for those who seek beatitude, and, what is worse, they take up very precious time that ought to be given to what is spiritually beneficial."

St. Basil, Hexaemeron: “Those who have written about the nature of the universe have discussed at length the shape of the earth… It will not lead me to give less importance to the creation of the universe, that the servant of God, Moses, is silent as to shapes…He has passed over in silence, as useless, all that is unimportant for us. Shall I then prefer foolish wisdom to the oracles of the Holy Spirit? Shall I not rather exalt Him who, not wishing to fill our minds with these vanities, has regulated all the economy of Scripture in view of the edification and the making perfect of our souls? It is this which those seem to me not to have understood, who, giving themselves up to the distorted meaning of allegory, have undertaken to give a majesty of their own invention to Scripture. It is to believe themselves wiser than the Holy Spirit, and to bring forth their own ideas under a pretext of exegesis. Let us hear Scripture as it has been written.”

I would also like to add that if one were to try to draw the flat Earth interpretation from Scripture, one would run into different contradictions. I've mentioned these before in previous threads.

LEO XIII: “Wherefore, it is clear that that interpretation must be rejected as senseless and false, which either makes inspired authors in some manner quarrel among themselves, or opposes the teaching of the Church. . . .”

There are few that one can point to it being their opinion. Lactantius is the only one which claims it's a matter of faith. St. Basil and St. Augustine explicitly say this topic is not in Scripture and is not worthy of serious thought. No one's saying they were ignorant. The ones who did hold the FE opinion seemed to hold it not as a matter of faith, but as the common opinion where they were. Like I said though, there weren't that many who wrote about it.
The only reason it's debatable is because the FE's are trying to destroy all credibility of the Church, so they try to tie it into the Catholic Faith. They get Catholics to believe in it by exaggerating the importance among the Fathers and twisting Scripture to attempt to make it a religious matter. There's a reason why this subject was not brought up for about 1500 years.

There are few that one can point to it being their opinion. Lactantius is the only one which claims it's a matter of faith. St. Basil and St. Augustine explicitly say this topic is not in Scripture and is not worthy of serious thought. No one's saying they were ignorant. The ones who did hold the FE opinion seemed to hold it not as a matter of faith, but as the common opinion where they were. Like I said though, there weren't that many who wrote about it.
The only reason it's debatable is because the FE's are trying to destroy all credibility of the Church, so they try to tie it into the Catholic Faith. They get Catholics to believe in it by exaggerating the importance among the Fathers and twisting Scripture to attempt to make it a religious matter. There's a reason why this subject was not brought up for about 1500 years.

I won't be surprised if Ladislaus conveniently ignores this question.

But it can be credibly interpreted as describing neither one, i.e. not attempting to describe the shape of the earth at all.

The use of the word "firmament" does not necessary imply that the author believes the earth is flat with a dome.  The term was co-opted by Catholics who accepted traditional geocentrism to describe a sphere surrounding the spherical earth.  Neither does rejection of antipodes imply belief in flat earth.  You keep seeing support for flat earth is passages that do not actually support it, giving you an exaggerated sense of just how much of this existed.

The "trend in the Church" is that belief in flat earth disappeared for over a thousand years.  There is no reason to take it seriously based on appeals to Catholic belief.  If you have good science arguments for flat earth, go ahead and make them.  Pretending that it is backed by the Church just destroys your credibility.

Can you give an opinion from a Catholic authority (Saints, Doctors, magisterial sources) any time after 700 that suggests that the earth is flat?

Genuine Catholic opinions persist throughout time.  They do not disappear for a thousand years and then get revived by heretics and promoted by pagans.  That is not spin.