You state:
The Church teaches that the entire deposit of faith was given at Pentecost, and our understanding thereof is what grows over time.
It is rather clear that the canon is closed for the CC and evangelicals, however, there are statements from both groups indicating that they receive "divine guidance" for interpreting the canon. After all, where else can you receive "divine guidance" except from the divine, and where else can you receive understanding of the things of God, but from God.
Quite correct, it is God the Holy Spirit that gives us Catholics guidance in these areas. The guidance given isn't "new revelation" however. It's guidance that protects us from erroneous interpretations/understandings (via the councils and Popes' vis a vis ex cathedra), and thus, He increases our understanding of the original deposit given at Pentecost.
You may be wondering, "Why not just call this 'guidance', 'revelation'?" This is to be certain to never confuse anyone by misleading them into believing we Catholics believe there are "prophets for today". There are no prophets for today who's words would be considered the Word of God. Knowing this however, if one wishes, one could describe the events of the Councils and the Papal decrees as "revelations", but only insomuch as to not confuse them with the Word of God. The ex cathedral and conciliar decrees are not the Word of God; they are clarifications of the original deposit of faith meant to teach us more about the original deposit, not to "reveal new doctrine".