Suppose a person moves to a new parish, attends Mass, follows along and notices that the priest routinely changes the Mass; omits the Creed (no Nicene, no Apostles, no renewal of baptismal promises), makes up his own Eucharistic prayers including changing the words of the consecration. . . writes to the priest politely saying that he/she was at Mass and noticed the above while following in the Missalette and asks the priest "why the change’, and priest politely responds with a thanks for attending Mass, invites the person 'not to follow along in the Missalette part of the songbook because active participation in the liturgy is how the people are called to be disciples of Christ;, and ends with have a blessed day.
My hypothetical is, what is the person’s responsibility now?