So you are saying that the West was so rife with heresies and divisions that during the second millennium they required almost double the number of Ecumenical Councils which were required to maintain a unified Christian Ecumene in the first millennium?
Satan got very vicious in the second millenium. Further since the church existed in the west it just ur Esther due such councils to be held
Lateran I - convened to: (a) bring an end to the practice of the conferring of ecclesiastical benefices by people who were laymen; (b) free the election of bishops and abbots from secular influence; (c) clarify the separation of spiritual and temporal affairs; (d) re-establish the principle that spiritual authority resides solely in the Church; (e) abolish the claim of the emperors to influence papal elections.
Lateran II - called primarily to neutralise the after-effects of the schism which had arisen after the death of Pope Honorius II as well as condemn various novel teachings of the Petrobrusians and the Henricians
Lateran III - convened by Pope Alexander III to deal with the after effects of the recent schism caused by Antipope Victor IV and the further two antipopes who succeeded him. It also condemned the condemned the Cathar heresies and pushed for the restoration of ecclesiastical discipline as well as condemned Sodomy official
Lateran IV - Called for mainly secular matters as it was called by Pope Innocent III because of the limited results of the Third and Fourth. Crusades as well as the elevation of Frederick II to the place Holy Roman Emperor.
Lyon I - Pope Innocent IV called the council to excommunicated and depose the emperor Frederick II with
Ad Apostolicae Dignitatis Apicem, as well as the Portuguese King Sancho II. It also called for a nee crusaded.
Lyon II - Called to resolve the Greek schism and the conquest of the Holy Lands
Vienne - Convened to withdraw papal support for the Knights Templar on the instigation of Philip IV of Francis and to deal with other issues for improvements in the life of the Church
Constance - Called to the solve the Great western schism and for the condemnation of Jan Hus his teachings.
Florence - Called primarily to resolve the Greek schism and provide military aid to Byzantium. Also formed brief unions with the Syrians, Copts and Ethiopians.
Lateran V - Convoked by Pope Julius II in response to a council summoned at Pisa by a group of cardinals who were hostile to the Pope. The council had reform as its chief concern. It restored peace among warring Christian rulers and sanctioned a new concordat with France to supersede the Pragmatic Sanction of Bourges. The council affirmed the immortality of the soul and condemned Conciliarism
Trent- Called to deal with the heresy of Protestantism
Vatican I - It was convoked to deal with the contemporary problems of the rising influence of rationalism, liberalism, and materialism. It dealt with the definition of the Catholic doctrine concerning the Church of Christ (dealt with under under the
Dogmatic Constitution on the Catholic Faith and
the First Dogmatic Constitution on the Church of Christ)
Vatican II - To define the ecclesiology if the Church which was unfinished at Vatican I due to its abrupt end. It was also called to address relations between the Catholic Church and the modern world.