In this last section (Defects and Remedies), there are some important things to note. First, after describing the graviora delicta, all of them serious sins against the Eucharist, there is a list of "Grave Matters" which identifies as "grave matter" issues identified through a list of specific paragraphs within the Instruction itself. So, there is no doubt left that the Apostolic See considers certain things "grave matter" and instructs bishops to correct them. Then RS says that it is the bishop’s responsibility, "within the limits of his competence, to issue norms on liturgical matters by which all are bound" and that he "is bound to promote the discipline common to the entire Church and therefore to insist upon the observance of all ecclesiastical laws" and moreover, "be watchful lest abuses encroach upon ecclesiastical discipline, especially as regards the ministry of the Word, the celebration of the Sacraments and sacramentals, the worship of God and the veneration of the Saints" (177). Furthermore, and this is precise:For those who want to understand exactly what is meant by the term 'Reprobated", Fr. Z explains it very well:
"Delicts against the faith as well as graviora delicta committed in the celebration of the Eucharist and the other Sacraments are to be referred without delay to the Congregation for the Doctrine of the Faith, which ‘examines [them] and, if necessary, proceeds to the declaration or imposition of canonical sanctions according to the norm of common or proper law’" (179 — emphasis added).
This means that the CDF has competence regarding some doctrinal issues of the sacraments and only the CDF has the faculty, from the Pope, to absolve certain sanctions incurred from committing graviora delicta. Then the Instruction says what the job of the CDW is.
One of the most important things to take note of when reading RS is use of forms of the Latin word reprobare, "to reprobate," in the English version. You will see that word in the quotation from paragraph 185, emphasized above. "Reprobare . . . to reprobate" is a technical legal term in Church law. What "reprobating" something does is effectively outlaw a practice in such a way that it is completely excluded. That is, once something is officially reprobated, you cannot make an appeal to "custom," saying "this is how we have done it for years . . . there is a custom." Once something is explicitly reprobated, it is out for good. There are nine uses of a form of reprobare in the Latin text identifying specific things. Among the most salient for the English-speaking world:A good read, highly recommended. Article is here.
"55. In some places there has existed an abuse by which the Priest breaks the host at the time of the consecration in the Holy Mass. This abuse is contrary to the tradition of the Church. It is reprobated and is to be corrected with haste.
"59. The reprobated practice by which Priests, Deacons or the faithful here and there alter or vary at will the texts of the Sacred Liturgy that they are charged to pronounce, must cease. For in doing thus, they render the celebration of the Sacred Liturgy unstable, and not infrequently distort the authentic meaning of the Liturgy.
"65. It should be borne in mind that any previous norm that may have admitted non-ordained faithful to give the homily during the eucharistic celebration is to be considered abrogated by the norm of canon 767 §1. This practice is reprobated, so that it cannot be permitted to attain the force of custom.
"117. . . . Reprobated, therefore, is any practice of using for the celebration of Mass common vessels, or others lacking in quality, or devoid of all artistic merit or which are mere containers, as also other vessels made from glass, earthenware, clay, or other materials that break easily. This norm is to be applied even as regards metals and other materials that easily rust or deteriorate.
"126. The abuse is reprobated whereby the sacred ministers celebrate Holy Mass or other rites without sacred vestments or with only a stole over the monastic cowl or the common habit of religious or ordinary clothes, contrary to the prescriptions of the liturgical books, even when there is only one minister participating. . . .
"157. . . . The practice of those Priests is reprobated who, even though present at the celebration, abstain from distributing Communion and hand this function over to laypersons."
Once reprobated, these abuses can never be considered licit through any claim of "custom" (e.g., "contra legem custom"). They must be corrected by the local bishops when encountered, for the sake of the salvation of souls (the motivating force of this Instruction). In addition to the things that are reprobated, there are also the graviora delicta and issues of grave matter.