As for saying it was never "required" by Rome for the Eastern Churches, well, maybe the anathemas were just a joke!
There were no anathemas requiring the use of the filioque. When the Emperor spoke at the Council of Florence, he said "it being understood that the Latins do not compel us to make any addition to the holy Creed, or to change any of the customs of our Church," a condition agreed on by the Latins.
"There were no anathemas requiring the use of the filioque."
That's just sophistry. Here's what Lyons II said:
" 1. On the supreme Trinity and the catholic faith
1. We profess faithfully and devotedly that the holy Spirit proceeds eternally from the Father and the Son, not as from two principles, but as from one principle; not by two spirations, but by one single spiration. This the holy Roman church, mother and mistress of all the faithful, has till now professed, preached and taught; this she firmly holds, preaches, professes and teaches; this is the unchangeable and true belief of the orthodox fathers and doctors, Latin and Greek alike. But because some, on account of ignorance of the said indisputable truth, have fallen into various errors, we, wishing to close the way to such errors, with the approval of the sacred council, condemn and reprove all who presume to deny that the holy Spirit proceeds eternally from the Father and the Son, or rashly to assert that the holy Spirit proceeds from the Father and the Son as from two principles and not as from one. "
If this is not a condemnation of the words of the Creed of 381, why do you suppose the Roman Catholic theologians in DC in 2003 felt compelled to write this recommendation:
"...that the Catholic Church, following a growing theological consensus, and in particular the statements made by Pope Paul VI, declare that the condemnation made at the Second Council of Lyons (1274) of those “who presume to deny that the Holy Spirit proceeds eternally from the Father and the Son” is no longer applicable."
Maybe they were kidding?