At the Council of Carthage in 379, a list of books allowed to be used in worship (Mass, Divine Liturgy) was finally finalized (sorta). For the Old Testament, they included all of the books in the common canon (the Jewish 22), but likewise the “five books of Solomon.” This includes Proverbs, Song of Solomon, Ecclesiastes, Wisdom of Solomon, and Sirach.
In part, it reads:
It was also determined that besides the Canonical Scriptures nothing be read in the Church under the title of divine Scriptures. The Canonical Scriptures are these: Genesis, Exodus, Leviticus, Numbers, Deuteronomy, Joshua the son of Nun, Judges, Ruth, four books of Kings, two books of Paraleipomena, Job, the Psalter, five books of Solomon, the books of the twelve prophets, Isaiah, Jeremiah, Ezekiel, Daniel, Tobit, Judith, Esther, two books of Esdras, two books of the Maccabees. Of the New Testament: four books of the Gospels, one book of the Acts of the Apostles, thirteen Epistles of the Apostle Paul, one epistle of the same to the Hebrews, two Epistles of the Apostle Peter, three of John, one of James, one of Jude, one book of the Apocalypse of John. Let this be made known also to our brother and fellow-priest Boniface, or to other bishops of those parts, for the purpose of confirming that Canon. because we have received from our fathers that those books must be read in the Church. Let it also be allowed that the Passions of Martyrs be read when their festivals are kept.
For the life of me, I don’t understand why Sirach is included rather than the Psalms of Solomon, but no one asked me but instead, for some reason, chose to listen to St. Augustine.
Anyway, the point of this is that there is a history of the “five books of Solomon” in Christian Tradition. Protestants, mostly, have removed the latter two. I say mostly, because the Anglicans (even the Episcopalians) and Lutherans still use it in their lectionary.
By the way, if we are going by the historical meaning of canon and what it means for Scripture to be canonical, then if the books are approved for worship, then they are canonical. Granted, if we are to go by the ancient term, we also have to make allowance for local liturgies – so it is not necessarily anti-Christian to think that Luther could design a list of books for his local area. The same thing with Wesley, et al. If you are in communion with them, then that is your local area.
It really is a fascinating thing.