Following the Great Schism, what replaced the ecumenical councils' canons on art?

Following the Great Schism, what replaced the ecumenical councils' canons on art?

As far as the Catholic Church is concerned the Quinisext Council has not been formally endorsed. Thus it’s decisions have no baring in the West as ecclesiastical art is concerned. This council even condemned certain Roman ecclesiastical practices which are still in force in the Latin Church.

The Catholic Church took ecclesiastical art to have an organic development from day one in the history of the Church.

That Christians from the very beginning adorned their catacombs with paintings of Christ, of the saints, of scenes from the Bible and allegorical groups is too obvious and too well known for it to be necessary to insist upon the fact. The catacombs are the cradle of all Christian art. Since their discovery in the sixteenth century — on 31 May, 1578, an accident revealed part of the catacomb in the Via Salaria — and the investigation of their contents that has gone on steadily ever since, we are able to reconstruct an exact idea of the paintings that adorned them. That the first Christians had any sort of prejudice against images, pictures, or statues is a myth (defended amongst others by Erasmus) that has been abundantly dispelled by all students of Christian archaeology. The idea that they must have feared the danger of idolatry among their new converts is disproved in the simplest way by the pictures even statues, that remain from the first centuries. Even the Jewish Christians had no reason to be prejudiced against pictures, as we have seen; still less had the Gentile communities any such feeling. They accepted the art of their time and used it, as well as a poor and persecuted community could, to express their religious ideas. Roman pagan cemeteries and Jewish catacombs already showed the way; Christians followed these examples with natural modifications. From the second half of the first century to the time of Constantine they buried their dead and celebrated their rites in these underground chambers...And the catacombs were covered with paintings.

The idea that the Church of the first centuries was in any way prejudiced against pictures and statues is the most impossible fiction. After Constantine (306-37) there was of course an enormous development of every kind. Instead of burrowing catacombs Christians began to build splendid basilicas. They adorned them with costly mosaics, carving, and statues. But there was no new principle. The mosaics represented more artistically and richly the motives that had been painted on the walls of the old caves, the larger statues continue the tradition begun by carved sarcophagi and little lead and glass ornaments. From that time to the Iconoclast Persecution holy images are in possession all over the Christian world. St. Ambrose (d. 397) describes in a letter how St. Paul appeared to him one night, and he recognized him by the likeness to his pictures (Ep. ii, in P.L., XVII, 821). St. Augustine (d. 430) refers several times to pictures of our Lord and the saints in churches (e.g. "De cons. Evang.", x in P.L., XXXIV, 1049; Reply to Faustus XXII.73); he says that some people even adore them ("De mor. eccl. cath.", xxxiv, P.L., XXXII, 1342). St. Jerome (d. 420) also writes of pictures of the Apostles as well-known ornaments of churches (In Ionam, iv). St. Paulinus of Nola (d. 431) paid for mosaics representing Biblical scenes and saints in the churches of his city, and then wrote a poem describing them (P.L., LXI, 884). Gregory of Tours (d. 594) says that a Frankish lady, who built a church of St. Stephen, showed the artists who painted its walls how they should represent the saints out of a book (Hist. Franc., II, 17, P.L., LXXI, 215). - Veneration of Images

In the East, the Eastern Churches employed icons as their main venue of Christian art as a legitimate practice, the West did not completely follow suit. The Western Churches continued to expand their art in both style and symbolism. The constant doctrine of the Church was defined at the Second Council of Nicaea (787), and is summed up in the often quoted formula: "The composition of the image is not the invention of the painters, but the result of the legislation and approved tradition of the Church" ("Synod Nicaea" II, Actio VI, 331, 832). It seems to be impossible to define more clearly the importance of art in the life of the Church, and at the same time its subordinate positions. This obviously, results one of the chief characteristics of religious painting, it’s conservative instinct and its tendency to hieratic formalism.

Thus even though the Quinisext Council (Canon 82) stated that Christ could not be depicted as a lamb, simply did not apply to the Roman Church. It’s canons clashed with western canons or practice, and the Church set them aside as representing as a Byzantine practice but lacking universal validity.

Christ as the Lamb of God (6th century)