Whether Paul VI was beatified, canonized, or not (which is an entirely separate discussion, but TL;DR: canonizations are secondary objects of the Church’s infallibility with regards to her universal ecclesiastical laws; a true Pope is protected by the Holy Ghost from declaring someone as a saint [and therefore eligible for the veneration of the laity, and the general worship in the liturgy] who in fact isn’t
; thus, if Francis is the Pope, then his beatification and canonization of Paul VI is legitimate), that has nothing to do with the papal authority to revise the liturgy.
(Just to be clear, I don’t think either Paul VI or Francis are true Popes. However, papal authority with regards to revising the liturgy and canonizations is still unchanged; if Paul VI was a true Pope, his revision of the Mass was legitimate and lawfully promulgated. If Francis is a true Pope, his beatification and canonization of Paul VI is likewise legitimate.)