“Who would not know that the holy canonical scriptures both of the Old and New Testament have a priority over all subsequent writings of bishops such that there cannot be any doubt or dispute at all as to whether whatever is written there is true or right; but that the writings of bishops after the settlement of the canon may be refuted both by the perhaps wiser words of anyone more experienced in the matter and by the weightier authority and more scholarly prudence of other bishops, and also by councils, if something in them perhaps has deviated from the truth; and that even councils held in particular regions or provinces must give way without quibbling (sine ullis ambagibus cedere) to the authority of plenary councils of the whole Christian world; and that even the earlier plenary councils are often (saepe) corrected (emendari) by later ones, if as a result of practical experience (cum aliquo experimento rerum) something that was closed is opened, something that was hidden has become known?”
Firstly, the “them” in bold refers to “the writings of bishops after the settlement of the canon”; this manifestly includes this quote from St. Augustine.
This is what I mean by the OP interpretation being self-refuting.
Beyond that, St Augustine in this passage clearly makes the case for the hierarchy of the Church in formulating doctrine. It is no accident this passage is from his argument against the Donatists, who tried to overturn this hierarchy by placing their local ruling over that of the rest of the Church.
St Augustine did not agree that everyone has equal standing to interpret Scripture, nor that doctrine and dogma had to be based in it. Indeed, the very notion of the New Testament canon is a conciliar ruling; St Augustine respected the precedent.
You are reading far too much into “corrected” and not accounting enough for the difference between dogma and doctrine.
Poor St Augustine—he’s been made a heretic retroactively nearly as often as St Paul.