In these sections of Mediator Dei, Pope Pius XII draws a parallel between dogma and liturgy:
63. Clearly no sincere Catholic can refuse to accept the formulation of Christian doctrine more recently elaborated and proclaimed as dogmas by the Church, under the inspiration and guidance of the Holy Spirit with abundant fruit for souls, because it pleases him to hark back to the old formulas. No more can any Catholic in his right senses repudiate existing legislation of the Church to revert to prescriptions based on the earliest sources of canon law. Just as obviously unwise and mistaken is the zeal of one who in matters liturgical would go back to the rites and usage of antiquity, discarding the new patterns introduced by disposition of divine Providence to meet the changes of circumstances and situation.
The main question, it seems, is how this is applied or not so much by traditional-leaning Catholics to the modern Roman Rite. Are the Vatican II reforms, as enacted, “providential,” and are those criticizing them “unwise and mistaken in zeal”?
I was unfamiliar with the Synod of Pistoia, but the 1786 meeting is cited negatively:
64. This way of acting bids fair to revive the exaggerated and senseless antiquarianism to which the illegal Council of Pistoia gave rise. It likewise attempts to reinstate a series of errors which were responsible for the calling of that meeting as well as for those resulting from it, with grievous harm to souls, and which the Church, the ever watchful guardian of the “deposit of faith” committed to her charge by her divine Founder, had every right and reason to condemn.[Cf. Pius VI, Constitution Auctorem fidei, August 28, 1794, nn. 31-34, 39, 62, 66, 69-74] For perverse designs and ventures of this sort tend to paralyze and weaken that process of sanctification by which the sacred liturgy directs the (children) of adoption to their Heavenly Father of their souls’ salvation.
Yes and no. Local and regional efforts that lack scholarly background and ample discernment: these could have good ideas blundered about. But the liturgy, as Pius XII concedes, was not given in exact form by the Lord, and many developments have taken place, and might well continue to take place in the centuries and millennia to come.