That's highly unlikely. The index's principle role was regarding doctrine.
The docuмent itself does not give the reason for removing the reference to Lactatianus's belief in flat earth, so we are speculating. You are here implying that we can deduce the reason based on flat earth being a matter of doctrine. In syllogism form, your argument would be:
The Index removed a passage containing a disagreement with flat earth.
The Index deals with doctrine.
The flat earth is a doctrine.
Therefore the reason for the removal of the passage is that it contains a disagreement with flat earth.
In your first post, however, you were trying to show this removal as evidence that the shape of the earth must be a matter of doctrine. In syllogism form:
The Index removed a passage because it contained a disagreement with flat earth.
The Index deals with doctrine.
Therefore flat earth is a doctrine.
You are using the same statement as both a proposition and a conclusion, i.e. the fallacy of
petitio principii or circular reasoning. You have to assume the thing that you are trying to prove.
There is, in fact, no basis for considering this docuмent as evidence that the Congregation of the Index considered flat earth a doctrine. It is, rather, evidence for the contrary, since they use the expression
terrenus globus to refer to the earth.
You have repeatedly in other threads referred to belief in a spherical earth as a heresy. There is no justification for doing this. There is no magisterial teaching that says the earth is flat. Even in the Patristic period, the only time in history when significant numbers of educated Christian authors believed the earth to be flat, none of the Fathers taught that this was a matter of faith.
On the contrary, we have the statement of St. John Damascene, himself a Church Father, writing in
An Exposition of Orthodox Faith, a summary of the Faith expounded by those who went before him:
"Further, some hold that the earth is in the form of a sphere, others that it is in that of a cone. At all events it is much smaller than the heaven, and suspended almost like a point in its midst. And it will pass away and be changed." (Book II Ch 10) http://www.newadvent.org/fathers/33042.htmThis is, in context, a completely clear statement from a Church Father that believing in a spherical earth is compatible with orthodox faith and no flat earther here has ever shown authoritative Catholic teaching otherwise. There is no
de fide teaching and Christians are free to believe as we wish concerning the shape of the earth.