At least there is some sort of following of the Instruction Liturgiam Authenticam published 25 April 2001:
“108. Sung texts and liturgical hymns have a particular importance and efficacy. Especially on Sunday, the “Day of the Lord”, the singing of the faithful gathered for the celebration of Holy Mass, no less than the prayers, the readings and the homily, express in an authentic way the message of the Liturgy while fostering a sense of common faith and communion in charity. If they are used widely by the faithful, they should remain relatively fixed so that confusion among the people may be avoided. Within five years from the publication of this Instruction, the Conferences of Bishops, necessarily in collaboration with the national and diocesan Commissions and with other experts, shall provide for the publication of a directory or repertory of texts intended for liturgical singing. This document shall be transmitted for the necessary recognitio to the Congregation for Divine Worship and the Discipline of the Sacraments.”
(The full document is at vatican.va/roman_curia/congregations/ccdds/documents/rc_con_ccdds_doc_20010507_liturgiam-authenticam_en.html ).
From the Media Release, the difference seems to be that insteading of having a “repertory of texts intended for liturgical singing” this list seems to have no force:
“Within three years, the Committee on the Liturgy will formulate a Common Repertoire of Liturgical Songs for use in all places where the Roman liturgy is celebrated in the United States of America. While songs outside the core repertoire may also be used in the Liturgy, this core repertoire will be included in all worship aids used in the dioceses of the United States of America.” (Media release at usccb.org/comm/archives/2006/06-201.shtml ,emphasis added.)
Another quote from Media Release: “The directory is to serve not so much as a list of approved and unapproved songs as a process by which bishops might regulate the quality of the text of songs composed for use in the liturgy.”
Another question is “why delay?”. The Vatican wanted a list of hymns by 25 April 2006. Why vote on norms? Why do the norms “require a two-thirds vote by the bishops”? Why prepare the list within three years, instead of three months or three days?
But at least the USCCB now seems to have a process for following a challenging Instruction from the Vatican.