This passage from St. Pius V’s Quo Primum seems to give the Holy See the authority over local liturgical tradition:
"Let all everywhere adopt and observe what has been handed down by the Holy Roman Church, the Mother and Teacher of the other churches, and let Masses not be sung or read according to any other formula than that of this Missal published by Us. This ordinance applies henceforth, now, and forever, throughout all the provinces of the Christian world, to all patriarchs, cathedral churches, collegiate and parish churches, be they secular or religious, both of men and of women - even of military orders - and of churches or chapels without a specific congregation in which conventual Masses are sung aloud in choir or read privately in accord with the rites and customs of the Roman Church. This Missal is to be used by all churches, even by those which in their authorization are made exempt, whether by Apostolic indult, custom, or privilege, or even if by oath or official confirmation of the Holy See, or have their rights and faculties guaranteed to them by any other manner whatsoever.
This new rite alone is to be used unless approval of the practice of saying Mass differently was given at the very time of the institution and confirmation of the church by Apostolic See at least 200 years ago, or unless there has prevailed a custom of a similar kind which has been continuously followed for a period of not less than 200 years, in which most cases We in no wise rescind their above-mentioned prerogative or custom. However, if this Missal, which we have seen fit to publish, be more agreeable to these latter, We grant them permission to celebrate Mass according to its rite, provided they have the consent of their bishop or prelate or of their whole Chapter, everything else to the contrary notwithstanding.
All other of the churches referred to above, however, are hereby denied the use of other missals, which are to be discontinued entirely and absolutely; whereas, by this present Constitution, which will be valid henceforth, now, and forever, We order and enjoin that nothing must be added to Our recently published Missal, nothing omitted from it, nor anything whatsoever be changed within it under the penalty of Our displeasure.
We specifically command each and every patriarch, administrator, and all other persons or whatever ecclesiastical dignity they may be, be they even cardinals of the Holy Roman Church, or possessed of any other rank or pre-eminence, and We order them in virtue of holy obedience to chant or to read the Mass according to the rite and manner and norm herewith laid down by Us and, hereafter, to discontinue and completely discard all other rubrics and rites of other missals, however ancient, which they have customarily followed; and they must not in celebrating Mass presume to introduce any ceremonies or recite any prayers other than those contained in this Missal."
Bl. Pius IX also seems to reserve authority over all rites to the Apostolic See in his encyclical Omnem Sollicitudinem:
"Therefore, as this same Supreme Pontiff declared, “that rule must be absolutely observed which states that, except for the most serious reasons and with the Apostolic See, no innovations are to be introduced into the holy rites of the liturgy, even under the pretext of restoring ceremonies which may seem to be more in conformity with liturgies approved by the same See.”
(We may disagree that the changes made were done for a serious reason, but it can be done with approval of the Holy See–why would this be if the Holy See did not have authority over liturgical rites?)
Again, he seems to give the Apostolic See authority over liturgical rites:
“Some of these rites have been used from time immemorial, others solemnly confirmed by the sanction of the Synod of Zamosi, which had the approbation of the Apostolic See.”
And again, we see that even organic changes are subject to the Apostolic See–how could statements like this be made if the Pope did not have authority over the liturgy?
“Our Predecessors, the Roman Pontiffs, have frequently and purposefully agreed to approve or permit those rites insofar as they in no way oppose the Catholic faith nor cause danger to souls nor derogate from ecclesiastical dignity.”[8] At the same time these canons have solemnly declared that no one whosoever, without consultation with this Holy See, may introduce even the slightest innovations into the liturgy."
As much as we may think the innovations in the 1969 missal are bad, innovations to the liturgy can be approved by the Pope. As much aas we or even previous popes may not have approved of the most recent changes, the current popes in their judgement have.