You realize of course that it is the Liturgical Movement that restored Gregorian chant to pride of place in the liturgy?
By the 19th century, it had fallen into disrepair and liturgical music was a regional mishmash. Spurred on by Dom Prosper Guéranger, the monks of Solesmes went back to ancient manuscripts and came up with a relatively standardized approach to interpretation. Another great patron of the Liturgical Movement, Pius X, deemed that the Solesmes method was the one to be adopted by the Roman Church. This led to the publication, in 1908, of the Vatican Edition of the Roman Gradual.
Solesmes are still the publishers of the official source of Gregorian chant for both the Mass and the Divine Office. The post-Conciliar 1974 Roman Gradual is essentially the 1908 rearranged for the new calendar and three year cycle of readings. For the post-Conciliar Divine Office, they produced the 1980 Psalterium Monasticum, the 1983 Liber Hymnarius, the 2005 Antiphonale Monasticum, the 2008 Les Heures Grégoriennes (for the clerics of St. Martin in France), and the 2010 Antiphonale Romanum.
These are all direct influences of the Liturgical Movement. Have there been controversies? To be sure, beginning with the Breviary of Pius X, nearly as controversial in its time as the Liturgy of the Hours. Even within the Solemnes, there were differing schools of thought on interpretation (“chant wars”), and the result didn’t please everyone. Where is man, one also finds man’s foibles.
That will never change, this discussion is proof of that.