Those who are looking from the fence can realize the plain falsehood of this statement and this is just a quick example among many.
Here is the canon in question:

Please read what is explicitly stated. This is not a mere "supervision" function. The canon is very clear that the Holy See alone has the right to ENACT the form of the Sacred Liturgy. Enacting is not merely supervising.
Looking at the dictionary definition of the word ENACT:
Make (a bill or other proposal) law.
"Make" is not the same as "supervise".
Cantarella,
Just a short comment on your approach to this problem. You are not presenting an argument. You are offering yourself as an "expert" to set your opinion against the opinion of Msgr. Klaus Gamber who was generally recognized and accepted as great liturgist.
I know of canon lawyers that you could quote who would agree with you completely. For example in 2001, John M. Huels, OSM, JCD, who at the time was a Servite priest, influential liturgical canonist, professor of canon law and vice-dean of Saint Paul University in Ottawa. His his opinion was published by the Canon Law Society of America. Your opinion is in perfect agreement with Huels.
I do not agree with Huels but I acknowledged that he was a recognized "expert" so when I disagree with his opinions, I have to offer reasoned arguments from higher authority to canon law, or at a minimum, produce a comparatively qualified expert who disagrees.
That's how it works.
Drew