I don't see the book of Baruch listed in the canons of Carthage or Hippo. What's the deal?
Baruch wasn’t left out. Besides being a prophet himself, Baruch served as the prophet Jeremiah’s scribe. The books of Baruch and Lamentations—which also known as “The Lamentations of Jeremiah”—were sometimes referred to collectively as “Jeremiah” in canonical lists of the early Church. We see the close relationship between these biblical books in canon 60 of the Council of Laodicea, which scholars estimate took place between A.D. 343 and 380. Jeremiah is listed with Baruch and Lamentations, though all three are named.
In the 39th Festal Letter of St. Athanasius (A.D. 367), Athanasius lists “Jeremias, and along with it, Baruch, Lamentations, and the Letter.” The “Letter” refers to the Letter of Jeremiah, which is appended as the sixth chapter of Baruch in Catholic Bibles and other Bibles, including the King James Version, although the latter doesn’t place it in the biblical canon. In addition, in St. Cyril of Jerusalem’s 4th Catechetical Lecture (circa A.D. 350), Jeremiah is treated as one book: “of Jeremias, one, along with Baruch, Lamentations and the Letter.”
J.E. Steinmueller notes that the prophet Daniel “states explicitly that he read in Jeremias the number of the years of the captivity” and “then in the same context he literally depends upon Baruch” (A Companion to Scripture Studies, vol. I, A General Introduction to the Bible 77). The passage is Daniel 9:2. In addition, Steinmueller says: “Modern scholars also point out that one and the same translator translated Jeremias, Baruch, and the Epistle of Jeremias from the Hebrew into the Greek, and thus these three books had been considered as one, a fact that is also confirmed by early church documents” (Ibid., emphasis added).
The canonical lists of the Councils of Hippo (A.D. 393) and Carthage (A.D. 397) would be such examples.