No, it's very clear, at least to the catechized, that any authority to retain or remit sins by the priest is granted under the gospel passage that you quoted. It is true he says the words "I absolve you", but if anyone doesn't understand that the absolution is granted by God then they are poorly catechized. All sin is against God, forgiveness can only come from God.
Now, as to whether the Holy Spirit procedes from the Father AND the Son, on that we'll have to agree to disagree.
"It is true he says the words "I absolve you", but if anyone doesn't understand that the absolution is granted by God then they are poorly catechized. All sin is against God, forgiveness can only come from God."
That's not the point. The question is whether the sacrament "creates" grace which is then imparted by The Church in the person of the priest or if the grace is uncreated as an essence of God and flows through the sacrament in the presence of the priest. Notions of created grace, like the impression created by the near absence of an epiklesis in certain Latin Rite liturgies, make sacraments into magic and priests into magicians.
"Now, as to whether the Holy Spirit procedes from the Father AND the Son, on that we'll have to agree to disagree."
Your theologians have determined that the Creed without the filioque innovation is "normative" and should be the prefered wording used for catchesis purposes. There may be those who still think the filioque is theologically correct as traditionally taught, but I suspect that they are few and far between. That said, because of the official explanation which the Latin Church now gives for the filioque, it is no longer proper to call it heretical, or so your hierarchs and mine have determined, which is good enough for me. The Eastern Rite Churches in communion with Rome, save perhaps for the Maronites, do not use the filioque.