“Facts are facts.”
Just because the Roman Church says so does not make it fact.
For example, the claim that the “Jewish canon” was determined at “Jamnia” is at very best, a “hypothetical”. It’s a Roman Catholic fantasy or worse.
The problem with your assertion is it is not just the Latin church saying this.
The longer canon of Scripture is not just used by the Latins (as an Orthodox Christian, I deny their claim to catholicity, will allow them a claim to Romanness since they got the original capital, while we got the Empire until it fell, but prefer, after the manner of the Father at the time of the schism of the Patriarchate of Rome from the Church, to call them Latins), but by Orthodox Christians and most of the Monophysites (Copts, Jacobites and Armenians) — the Ethiopians having an even longer canon.
I do not know what account the Copts give of the fixing of the canon of Scripture, but the account we Orthodox give is this: a local council of at Carthage in, I believe 419, set forth in one of its canons a list of the books to be read in the Churches containing the universally agreed New Testament Scriptures and the books of the LXX as the Scriptures of the Old Testament. (I note at this point, the council which took place within the Patriarchate of Rome receive a Papal assent — the Latins’ with their theory of papal power regard this as having fixed the canon, but for us Orthodox, at this point, it was a purely local decision binding on at most the Patriarchate of Rome, perhaps only the local church of Carthage, and subject to review or revision by the Church as a whole.)
This local decision was explicitly given universal force throughout the Church by the disciplinary session of the Sixth Ecumenical Council in, if I recall correctly, 681 — Westerners often call the disciplinary session of the Sixth Ecumenical Council the “Quinsext Council” — which, in one of its canons, specifically directed that the canons of a list of local councils including Carthage be received throughout the Church. Most Orthodox hold that this is the action which fixed the canon of Scripture, though some hold that a canon of the Council of Chalcedon (451) which makes reference to “the ancient canons” had the same force — I am dubious that the canons of a council held a mere 32 years earlier would be regarded as “ancient”.
To Mr Rogers’ question: “Apocrypha” is what protestants call the books, “deuterocanonicals” are what Latins call them. We Orthodox, unless under Western influence, just call them books of the Old Testament.
To jjotto: No, while details of the Council of Jamnia are scholarly surmise, the fact that the Jewish canon was not fixed until after Our Lord’s earthly ministry is proven by the Dead Sea Scrolls, which contain Hebrew versions of books and chapters left out of the Masorete, and on average agree with the reading given by the LXX better than that in the Masorete (there are points where all three disagree, but more points where the LXX and Masorete agree on which the DSS support the LXX rather than the other way around).