Who is the Gelasius you refer to? Was he there? Or is he the much later writer, from the 5th century, whose account may or may not be historically accurate, given that he was not an eyewitness? Where does any of this suggest or prove that the Council’s authoritative and binding teachings involved the Bishop of Rome? Nowhere.
The Council of 381 A.D. could not be informed by the Creed at 451 A.D. Unless I misunderstand you? Sorry, I’m not clear on what you mean.
Many things can “seem very possible” but that is not proof nor fact.
Why do you consider the ecumenical Council of Constantinople a local eastern council as the Catholic Church (and almost all Christian Churches) consider it ecumenical?
Pope Damasus had nothing to do with Constantinople I (381 A.D.) did he?
Exactly. The Pope (Bishop of Rome) had no role.
Gelasius of Cyzicus is a writer ~ 475 A.D. and his works are of some importance. He wrote that Ossius “held the place of Sylvester of Rome, together with the Roman presbyters Vito and Vincentius.” No, he was not at Nicea (325 A.D.). That there were legates from Rome, means the Pope had a role.
CCC 247 The affirmation of the *filioque *does not appear in the Creed confessed in 381 at Constantinople. But Pope St. Leo I, following an ancient Latin and Alexandrian tradition, had already confessed it dogmatically in 447, [76]
even before Rome, in 451 at the Council of Chalcedon, came to recognize and receive the Symbol of 381. The use of this formula in the Creed was gradually admitted into the Latin liturgy (between the eighth and eleventh centuries). The introduction of the filioque into the Niceno-Constantinopolitan Creed by the Latin liturgy constitutes moreover, even today, a point of disagreement with the Orthodox Churches.
I posted previously: “Pope Damasus I summoned Eastern Bishops to Rome to settle issues due to dissatisfaction with the local council decisions.” This was after the Constantinople I met, and before ratifying it’s decisions.
Constantinople I (381 A.D.) was an eastern local council. Later some of the canons were accepted by the Supreme Pontiff and at it was ratified, so became ecumenical at that time. Gregory the Great, following the example of Vigilius and Pelagius II, recognized Constantinople I as one of the four general councils, in its dogmatic utterances (P.G., LXXVII, 468, 893).
Pope Celistine I did have a role at Ephesus (431 A.D.), he sent his legates, and the council reconvened with them and voted again. This is why the council is accepted by Rome.