St Augustine was accepted as a Father by the Ecumenical councils.
Anyone who does not accept him as a Saint and a Father is not Orthodox.
Not to belabour the point, but the letter of Saint Justinian the Emperor is included in the acts of the fifth Ecumenical Council and says:
"We further declare that we hold fast to the decrees of the four Councils, and in every way follow the holy fathers Athanasius, Hilary, Basil, Gregory the Theologian, Gregory of Nyssa, Ambrose, Theophilus, John of Constantinople, Cyril, Augustine
, Proclus, Leo and their writings on the true faith."
Furthermore, the sentence of the Council Fathers themselves says:
"Moreover several letters of Augustine, of most religious memory, who shone forth resplendent among the African bishops, were read, showing that it was quite right that heretics should be anathematized after death."
If Saint Augustine is a complete heretic it is odd that an Ecumenical Council is citing him as a basis for its decision and the emperor who convened it mentions him among saintly teachers of the Church in his letter to it.
Augustine is honourable for this willingness to admit his mistakes and submit to the judgement of the Church, and for his efforts to combat Donatism, Manichaeanism and Pelagianism.