Once Augustine understood that it was by grace he was saved, he recalled some of his works to be burned. This is written in the final writings of Augustine. He didn't burn anything. Shortly before his death, he examined some of his earlier works, yes, as Possidius tells us and the Retractations are still available to read. I haven't read them and they are hard to find online but I'll bet you there isn't anything in there that repudiates his earlier views on the episcopacy the Mass or anything else I mentioned.
Also, think it through...if he repudiated his Catholicism, why did Catholics canonize him and venerate him?
Perhaps "burned" is too strong of word. Augustine
retracted some of his works when he realized his error. He discusses this in Chapter 7 of the
Treatise on the Predestination of the Saints.
It was not thus that pious and humble teacher thought—I speak of the most blessed Cyprian—when he said "that we must boast in nothing, since nothing is our own." And in order to show the, he appealed to the apostle as a witness, where he said, "For what hast thou that thou hast not received? And if thou hast received it, why boastest thou as if thou hadst not received it?" And it was chiefly by this testimony that I myself also was convinced when I was in a similar error, thinking that faith whereby we believe on God is not God's gift, but that it is in us from ourselves, and that by it we obtain the gifts of God, whereby we may live temperately and righteously and piously in this world. For I did not think that faith was preceded by God's grace, so that by its means would be given to us what we might profitably ask, except that we could not believe if the proclamation of the truth did not precede; but that we should consent when the gospel was preached to us I thought was our own doing, and came to us from ourselves. And this my error is sufficiently indicated in some small works of mine written before my episcopate. Among these is that which you have mentioned in your letters wherein is an exposition of certain propositions from the Epistle to the Romans. Eventually, when I was retracting all my small works, and was committing that retractation to writing,of which task I had already completed two books before I had taken up your more lengthy letters-Augustine
Please note that Augustine finally understood that grace must proceed faith. And he finally understood this from one of the earliest church fathers-Cyprian.
So every time Catholics take the Eucharist to receive God's grace, they negate the work of Christ simply because they do not accept the grace that God has given them.