It’s not even about the council. You’re missing the whole point. It’s about the fact that the EO typically understand the canon of Ephesus to mean no additions may me made to the creed or that new creeds may be composed which is wrong completely. What the Council actually meant was that nobody can adjust the creed of change it in such a way that it teaches a new faith.
Yes I mentioned this fact in my first post that it’s the Nicene-Constantinopolitan creed. WE ALL KNOW THIS. A creed doesn’t need an ecumenical council to be adjusted. The canons of Ephesus do not say this anywhere. This is just a modern EO phenomenon which is made up to try and make their position less restrictive on the authority of the church. The church can adjust a creed as needs be to make explicit what was implicit so as to clarify the faith and refute error. No ecumenical council is needed. That’s all the filioque was.
The West was already adjusting the creed with the filioque addition by the 5th century. The popes never once denounced this practice on account of Ephesus or that it was being done without an ecumenical council but rather simply on account that the Greeks were very touchy about it and for the sake of harmony asked them to not add it to the creed. The Synod of Seleucia Ctesiphon (the territory of what is today the Assyrian Church of the east) is the first recorded filioque addition to the creed. The council of Toledo did the same and then various other councils as well as the local papal addition in the 11th century. The Armenian Church has additions of their own to the creed too.
In fact even Constantinople I, which made the additions to the creed of Nicaea as we know the creed today, was merely a local Synod at the time of Ephesus. It only got raised to ecumenical status at the council of Chalcedon. Which shows that even the Byzantine east believed that the creed could be adjusted without the need for an ecumenical council.
This just goes to show that nobody in the church understood the canon of Ephesus in the same way that the post-schism byzantines later did.