Compare the Protestants' position to that of the Apostles' with regard to the Deuterocanonicals.
As far as Jerome, he was persuaded to include the deuterocanonicals in his Vulgate since the books were so widely accepted by the Church. Refer to Jerome's defense of his inclusion of the parts of Daniel rejected by the Jews:
Jerome And The Apocrypha
Question: St Jerome was persuaded, against his original inclination, to include the deuterocanonicals in his Vulgate edition of the Scriptures. What are your comments?
Answer: True, yet he classed the Apocrypha in a separated category. He differentiated between the canonical books and ecclesiastical books, which he did not recognize as authoritative Scripture. This is admitted by the modern Catholic church:
“St. Jerome distinguished between canonical books and ecclesiastical books. The latter he judged were circulated by the Church as good spiritual reading but were not recognized as authoritative Scripture. The situation remained unclear in the ensuing centuries...For example, John of Damascus, Gregory the Great, Walafrid, Nicolas of Lyra and Tostado continued to doubt the canonicity of the deuterocanonical books. According to Catholic doctrine, the proximate criterion of the biblical canon is the infallible decision of the Church. This decision was not given until rather late in the history of the Church at the Council of Trent. The Council of Trent definitively settled the matter of the Old Testament Canon. That this had not been done previously is apparent from the uncertainty that persisted up to the time of Trent” (The New Catholic Encyclopedia, The Canon).
The practice of the Church up to the time of the Reformation was to follow the judgment of Jerome who rejected the Old Testament apocrypha on the grounds that these books were never part of the Jewish canon. These were permissible to be read in the churches for the purposes of edification but were never considered authoritative for establishing doctrine. The Protestants did nothing new when they rejected the apocrypha as authoritative Scripture. It was the Roman church that rejected this tradition and ‘canonized’ the ecclesiastical books.
Please read the following explanation from the Roman Catholic Cardinal Cajetan, a contemporary of Martin Luther:
"Here we close our commentaries on the historical books of the Old Testament. For the rest (that is, Judith, Tobit, and the books of Maccabees) are counted by St. Jerome out of the canonical books, and are placed amongst the apocrypha, along with Wisdom and Ecciesiasticus, as is plain from the Protogus Galeatus. Nor be thou disturbed, like a raw scholar, if thou shouldest find anywhere, either in the sacred councils or the sacred doctors, these books reckoned as canonical. For the words as well of councils as of doctors are to be reduced to the correction of Jerome. Now, according to his judgment, in the epistle to the bishops Chromatius and Heliodorus, these books (and any other like books in the canon of the Bible) are not canonical, that is, not in the nature of a rule for confirming matters of faith. Yet, they may be called canonical, that is, in the nature of a rule for the edification of the faithful, as being received and authorised in the canon of the Bible for that purpose. By the help of this distinction thou mayest see thy way clearly through that which Augustine says, and what is written in the provincial council of Carthage." (Cardinal Cajetan, "Commentary on all the Authentic Historical Books of the Old Testament," cited by William Whitaker in "A Disputation on Holy Scripture," Cambridge: Parker Society (1849), p. 424)
The apocrypha are useful for edification, but canonical in the sense that they are the rule for confirming matters of faith, no!