The sermons of John Chrysostom became known to fathers such as Augustine at a very early date. Apparently a bunch of them were translated by the deacon Anianus of Celeda in the early 5th century. Emilio Bonfiglio has written a dissertation on the translations of Anianus, although I have not seen this, and it may be in Italian anyway.
Quasten’s Patrology gives Anianus as the translator of some of the sermons on Matthew, and the encomiums on St. Paul; but also of other works. It would be very interesting to learn more about this activity. We’re all familiar with the Latin translations that appear in Migne’s Patrologia Graeca opposite the Greek; but what proportion of these are in fact ancient translations, rather than renaissance?
I’ve managed to find online a paper about Anianus of Celeda, given by Kate Cooper and published in the papers of the Oxford Patristic Conference here. This tells us that he wrote a prefatory letter to each of those two translations (PG50, 472-3, to Evangelius before the Paul texts and PG58 975-6 to Orontius for the homilies). A new and rather different version of the letter to Orontius was uncovered in 1972 by Adolf Primmer (Die Originalfassung von Anianus’ epistula ad Orontium, in Antidosis: Festschrift für Walther Kraus, ed. R. Hanslik, A. Lesky, and H. Schwabl, 278–89. Vienna, 1982). It would certainly be worth getting an English version of these.