The canon of Scripture may not have been defined at an ecumenical council that early, and I don’t know if these local councils were definitive for the whole West, but the canon was more or less settled in the West at this point in time anyway. If you want an example of an ecumenical council prior to Trent, I know Florence listed the canon explicitly.
[The holy Roman Church] professes that one and the same God is the author of the old and the new Testament — that is, the law and the prophets, and the gospel — since the saints of both testaments spoke under the inspiration of the same Spirit. It accepts and venerates their books, whose titles are as follows.
Five books of Moses, namely Genesis, Exodus, Leviticus, Numbers, Deuteronomy; Joshua, Judges, Ruth, four books of Kings, two of Paralipomenon, Esdras, Nehemiah, Tobit, Judith, Esther, Job, Psalms of David, Proverbs, Ecclesiastes, Song of Songs, Wisdom, Ecclesiasticus, Isaiah, Jeremiah, Baruch, Ezechiel, Daniel; the twelve minor prophets, namely Hosea, Joel, Amos, Obadiah, Jonah, Micah, Nahum, Habakkuk, Zephaniah, Haggai, Zechariah, Malachi; two books of the Maccabees; the four gospels of Matthew, Mark, Luke and John; fourteen letters of Paul, to the Romans, two to the Corinthians, to the Galatians, to the Ephesians, to the Philippians, two to the Thessalonians, to the Colossians, two to Timothy, to Titus, to Philemon, to the Hebrews; two letters of Peter, three of John, one of James, one of Jude; Acts of the Apostles; Apocalypse of John.