How Do RC Theologians Regard The "Gnostic" Gospels?

The “Nag Hamadi” manscripts have been known for years now. They include a lot of writings that are termed “Gnostic”. Items like the Gospel of Thomas-are these seen as spurious?
Clearly, these texts are ancient, and someone went to great lengths to preserve them.
Yet, since they are not included in the Catholic New Testament, does this mean that:
-the RC rejects their contenst?
-or if authentic, these gospels carry a message that is irrelevant to RC teachings?
What is the chrch’s position on these books?

They’re, well, not spurious, because they really are gospels, but not canonical. They tend to have been written later and never were adopted by the ancient church as a whole.

Not exactly. If it’s not canon it’s not considered divinely inspired - the label “The Gospel of…” is a title given by the work itself, not by the Church. It would be called an “Apocryphal” gospel or book.

Doctrinally, none of the Apocryphal gospels or books are valid and therefore potentially heretical. Some of then were popular even throughout the Middle Ages after being rejected for inclusion in the canon (obviously they were candidates at some point) and tolerated by the church due to their providing stories or parables that, while not “inspired”, were still in line with doctrine (such as filler detail like giving the names of the Three Wise Men being Melchior, Caspar and Balthazar, which is not actually in any of the “real” Bible books). Sometimes you see artwork depicting a scene from an Apocryphal book too.

But others were considered out and out heretical and to be stamped out. Most of the Gnostic texts fell into this category - the Gnostic sects of early Christianity held some fundamentally different views on the nature and relationship of Christ, the Godhead and Man.