One can debate decisions of local councils indeed, with the guidance of the Church. There probably was a point when Luther, too, was within his right to debate his ideas and remain Catholic. Then, he crossed that line into heresy and blasphemy. I do not have enough interest in that jerk to discuss with you when and how.
And which means that the African canon was not binding, and that canonical status of books that Trent later affirmed as being Scripture proper was still subject to debate up to that point. Which was the point, contrary to your assertions.
There probably was a point when Luther, too, was within his right to debate his ideas and remain Catholic.
There is no probably in regards to the canon, and Catholics are guilty here of reading back into history the idea that his expressly non-biding view on the canon was part of his official censure. For the fact remains that the only indisputable (as far as Rome is concerned) definition of the canon occurred after the death of Luther in 1546
Then, he crossed that line into heresy and blasphemy.
Whatever you think that is. A church which teaches heresy and blasphemy yet judging another of such is self-condemned. If the preaching of the apostles could not have withstood the test of examination by Scripture, which must of Rome's doctrine cannot, then they would not be of God.
But the Catholic retort is "we gave you the Scriptures," and even that one is unable to discover the contents Scripture apart from faith in her, who must tell them, and thus questions must be asked regarding this premise.