While I’m not Catholic, and my understanding of council canons leaves
much to be desired, I do in fact read English fluently as a native speaker. I’m afraid your friend didn’t exercise his due diligence in reading comprehension.
In Session 7 On the Sacraments in General it states
CANON XIII.-If any one saith, that the received and approved rites of the Catholic Church, wont to be used in the solemn [Page 56] administration of the sacraments, may be contemned, or without sin be omitted at pleasure by the ministers, or be changed, by every pastor of the churches, into other new ones; let him be anathema.
Even if we humor his interpretation of “every pastor” to include any and all Popes, any and all Dicasteries in the Vatican, and any and all Bishops in Ecumenical Council, he would
still be wrong to assume this applies to the Ordinary Form of the Mass.
If any one saith, that the received and approved rites of the Catholic Church, …]
The Ordinary Form of the Mass is a “received and approved rite of the Catholic Church” in and of itself. It isn’t some random deviation that was unilaterally created by a rogue priest, bishop, or even a Pope.
…] may be contemned, or without sin
be omitted at pleasure by the ministers, or be changed, by every pastor of the churches, into other new ones; let him be anathema.
Notice the part I put in bold and red font. “Be omitted
at pleasure by the ministers” clarifies exactly what is meant here as “change”. It isn’t talking about officially recognized deliberate change to the rites
by the Church as a whole, rather it’s talking about rogue individual celebrants making their own modifications to suit their
own tastes. In other words this canon seems to me to be saying “If anyone says it’s OK to commit a liturgical abuse (as the Church defines it) let him be anathema”.