In accord with no. 55 of the instruction of the Congregation of Rites on music in the liturgy

"55. It will be for the competent territorial authority to decide whether certain vernacular texts set to music which have been handed down from former times, can in fact be used, even though they may not conform in all details with the legitimately approved versions of the liturgical texts."

Music in Catholic Worship has been superceded (and did it have recognitio as particular law to begin with?), but Musicam Sacram has not been generally (though it has in some particulars.) The key question is whether it has been in this particular.

The force of law accorded to the passage cited comes from its incorporation into American adaptation of the General Instruction of the Roman Missal (first edition), made by the (then) National Conference of Catholic Bishops for the Dioceses of the United States and approved by the Holy See. The legal status of "Music in Catholic Worship" is moot, since the present edition of the Roman Missal in the US does not authorize the use of other translations of the Ordinary of the Mass in English and further requires that all musical settings be submitted to the Episcopal Conference for approval prior to their publication:

GIRM 393. Bearing in mind the important place that singing has in a celebration as a necessary or integral part of the Liturgy, all musical settings for the texts of the Ordinary of Mass, for the people’s responses and acclamations, and for the special rites that occur in the course of the liturgical year must be submitted to the Secretariat of Divine Worship of the United States Conference of Catholic Bishops for review and approval prior to publication.

The Decree of Publication of the present edition of the Missal states that "The third edition of the Roman Missal enters into use in the dioceses of the United States of America as of the First Sunday of Advent, November 27, 2011. From that date forward, no other English edition of the Roman Missal may be used in the dioceses of the United States of America." Presumably this includes all the texts of the Missal. If the bishops wanted to allow earlier approved translations to be used in the celebration of Mass in English, they could very well have carried the previous instruction over into the third edition. That they did not seems to me to indicate that that permission has been abrogated. After all, the same rule could be applied to justify the continuing use of the old ICET translations, something that was clearly not envisioned, as the new translation itself was mandated by Liturgiam authenticam.