Parts of this answer is taken directly from the Catechism of the Catholic Church (1994) which carries the seal of Imprimi Potest, by which the Catholic Church recognizes the publication to be free of doctrinal error (as I understand it).
On the Inspiration and Truth of Sacred Scripture, attesting to divine authorship:
105 God is the author of Sacred Scripture. "The divinely revealed realities, which are contained and presented in the text of Sacred Scripture, have been written down under the inspiration of the Holy Spirit."
And attesting to inerrancy of all, including the deuterocanonical books (emphasis mine):
107 The inspired books teach the truth. "Since therefore all that
the inspired authors or sacred writers affirm should be regarded as
affirmed by the Holy Spirit, we must acknowledge that the books of
Scripture firmly, faithfully, and without error teach that truth
which God, for the sake of our salvation, wished to see confided to
the Sacred Scriptures."
Therefore, the books in question are viewed as inerrant and on the same level as the rest of the Biblical canon, old and new testaments.
To speak to Irawan's point as to how Catholics view scripture, the relationship between scripture and "tradition" is as follows (CCC 80 ff):
One common source. . .
80 "Sacred Tradition and Sacred Scripture, then, are bound closely
together, and communicate one with the other. For both of them,
flowing out from the same divine well-spring, come together in some
fashion to form one thing, and move towards the same goal."40 Each of
them makes present and fruitful in the Church the mystery of Christ,
who promised to remain with his own "always, to the close of the
age".
. . . two distinct modes of transmission
81 "Sacred Scripture is the speech of God as it is put down in writing
under the breath of the Holy Spirit."
"and [Holy] Tradition transmits in its entirety the Word of God which
has been entrusted to the apostles by Christ the Lord and the Holy
Spirit. It transmits it to the successors of the apostles so that,
enlightened by the Spirit of truth, they may faithfully preserve,
expound and spread it abroad by their preaching."
82 As a result the Church, to whom the transmission and interpretation
of Revelation is entrusted, "does not derive her certainty about all
revealed truths from the holy Scriptures alone. Both Scripture and
Tradition must be accepted and honoured with equal sentiments of
devotion and reverence."
Apostolic Tradition and ecclesial traditions
83 The Tradition here in question comes from the apostles and hands on
what they received from Jesus' teaching and example and what they
learned from the Holy Spirit. the first generation of Christians did
not yet have a written New Testament, and the New Testament itself
demonstrates the process of living Tradition.
Tradition is to be distinguished from the various theological,
disciplinary, liturgical or devotional traditions, born in the local
churches over time. These are the particular forms, adapted to
different places and times, in which the great Tradition is expressed.
In the light of Tradition, these traditions can be retained, modified
or even abandoned under the guidance of the Church's Magisterium.
The origins of the Catholic OT canon is rather a lengthy discussion, which can be found here. The gist of it is (emphasis mine):
It now seems more probable that at the time of Christianity's birth,
closed collections of the Law and the Prophets existed in a textual
form substantially identical with the Old Testament. The collection of
“Writings”, on the other hand, was not as well defined either in
Palestine or in the Jewish diaspora, with regard to the number of
books and their textual form. Towards the end of the first century
A.D., it seems that 22 books were generally accepted by Jews as
sacred, but it is only much later that the list became exclusive.
When the limits of the Hebrew canon were fixed, the deuterocanonical
books were not included.
...
In the West, the use of a larger collection of sacred books was common
and was defended by Augustine. When it came to selecting books to be
included in the canon, Augustine (354-430) based his judgement on the
constant practice of the Church. At the beginning of the fifth
century, councils adopted his position in drawing up the Old Testament
canon. Although these councils were regional, the unanimity expressed
in their lists represents Church usage in the West.
From this information, assuming it's in fact accurate, it could be argued that the reformers rejected an OT canon which the Christian Church had used for well over a millennia; I have read arguments by Catholic writers which suggest that the Jewish canon was altered (or perhaps finalized) well after the Christian church was established, but I cannot find references to support that.
