And here we get to the nub of the matter. When the Greeks re-encountered the Latins after the dark ages, they found them frequently hanging all theology upon St. Augustine. What they apparently still do not appreciate is that while the west has always revered St. Augustine as a great teacher, our second greatest doctor in fact after St. Thomas Aquinas, we do not follow him in all things.
St. Augustine, because of the myriad contrversies he involved himself in, was the first Latin Father to provide enough material for a systematic expostion of the Catholic Faith. He also stood up and put down the Pelagian heresy and systematized western thinking on grace and related topics. But, his excessive zeal lead to a need to correct his intemperance in protecting truth from error, something which began at once by his disciple St. Prosper of Aquitaine, who modified and molified many of his stances.
It seems to me the confusion comes in from our great reverance for St. Augustine in the west. Because we quote him so much as an authority on certain topics, the Greeks seem to assume he is to be taken as an authority for Catholicism on all things in his works without question. Not so. We are guided in all things only by the Sancta Romana Ecclesia - the Holy Roman Church - and NOT by St. Augustine.
"When anyone finds a doctrine clearly established in Augustine, he can absolutely hold and teach it, disregarding any bull of the Pope. ... Condemned and prohibited as rash, scandalous, evil-sounding, injurious, close to heresy, smacking of heresy, erroneous, schismatic, and heretical respectively." (Decree of the Holy Office, confirmed by Pope Alexander VIII, 7 December 1690)