Since filioque controversy did not “change” the faith of Nicea (as admitted to even by EO bishops), what of the disciplinary prohibition of the Council of Ephesus and Chalcedon not to change the creed?
Catholics interpret this prohibition as legislative or disciplinary in context, proscriptive of *individuals *changing the Creed of Nicea on their own individual authority. We don’t interpret the councils to have forbidden the Church as a body to explain the same faith or to propose the same Creed in a clearer way. The proscriptions of Ephesus and Chalcedon affected individual transgressors, as is plain from the sanction added. They did not bind the Church as a body which continued to authentically manifest its judgment in synods and councils, ecumenical or otherwise.
Consequently, those councils, such as the Third Synod of Toledo (589), Council of Friuli (796), and the Ecumenical Councils of Lyons (1274) and Florence (1439)–did not act contrary to these prohibitions, because they did not act upon individual authority, but with lawful Church authority, at first synodal then later ecumenical.