One must be careful not to confuse what is frequently called Augustinism, especially by the Jansenists, Calvinists, and Lutherans, and what Catholics have taken from St. Augustine and incorporated as an explanation of the Faith.
Every system of grace expounded in Catholic theology, Augustinism, Thomism, Molinism, Congruism, Syncretism (all approved), Jansenism (condemned) claims to be teaching the exact truths St. Augustine attempted to communicate. Obviously St. Augustine did not teach all (or perhaps even any) of them, nor can they all be correct.
In any case, Catholics are not "Augustinians".
Indeed they aren't. St. Augustine's teaching on the Original Sin is what is called Augustinianism; the Catholic doctrine on Original Sin was in consensus with the Greek Fathers prior to that, and returned to essentially the same teaching with St. Thomas Aquinas.
The term "Augustinian" is frequently used in the same sense I use it, not to discard the immense work of St. Augustine's overall, but to point out elements of his teaching that fell outside of the approved doctrine, by the Catholic Encyclopedia article I am referring to, Limbo.