As to what the Jewish canon (whatever that means) was at the time is simply irrelevant. Obviously they used Hebrew scriptures in their worship. We know that the deuterocanonicals specifically are inspired because St. Paul made a reference to "all scripture" without excluding anything and without qualifying the language, -- so that was then the Septuagint of the 1st century that is wholly inspired.
No, you’ve misunderstood. As I said before, Beckwith processes those patristic mentions. There is no contention that the books were individually written 4th Century. I didn’t say that, and Beckwith doesn’t say that. The contention is that their inclusion into any kind of canonical status didn’t happen First Century under the Jewish magisterium, but in the 4th Century, under ostensibly Christian scholarship. This precludes them from being part of the corpus of canonical text to which Paul was referring in his epistle to Timothy.
I can't believe I'm arguing this topic on two threads today!
You cannot come to the conclusion that every book that was in the Greek Septuagint automatically made them "wholly inspired". Are you forgetting that there were not seven but FIFTEEN books that were noncanonical for the Jews yet were included in the Septuagint? Is it your contention that Paul included them as well as inspired by God? That is a leap that not even your church would make into the Council of Trent fifteen HUNDRED years after Paul wrote to Timothy!