Yes, but the Athanasian Creed dates from the 7th Century, so if I were Greek Orthodox I would be making the same post. Must say the Greek speaks in less legalistic terms, so you might want to consult the Cappadocian Fathers to see how they talk about the Trinity.
To those of us who have studied the historical development of the trinity, the Athanasian Creed is not new to us, we have “gotten the handle on Trinitarianism” as you call it.
The creed stands at the end of a long process of development. Not something handed down historically from the apostles, mind you, but developed by step by step by such principle men as Justin, Tertullian, and Origen.
The Athanasian Creed, were it around in these men’s days, would have condemned them, none of them believed Father, son, Holy Spirit as defined in this creed.
Justin Martyr, a former pagan Greek philosopher and apologist, used the Logos of Plato as a means to defend Christianity, on one hand, a means to convert the masses heavily influenced by Greek philosophic thought, on the other.
Tertullian, who came later, building upon Justin, is famously known as the first to use “persons” and “Trinity” writing against Praxeus’ oneness belief.
Origen, who came later, following Justin and Tertullian before him, added the concept of the “eternal Son.” The councils came later, the Cappadocian Fathers you mentioned, and Augustine, giving us the final product.
I don’t buy any of it. The apostles were of the Jewish monotheist tradition, the pagan philosophy would have been abhorrent to them. John’s Logos was not Plato’s or Justin’s. They were neither Trinitarian nor Arian. I believe they were, what people call today, “Oneness Pentecostals.”