I cannot speak to EF rubrics in this matter, but thought it customary from of old that Te Deum was not sung during penitential seasons. There is, though, I think some question as to whether this stricture applies to all penitential seasons or just those in which Gloria is not sung. I think that the latter represents the more correct usage. It would make sense that hymn paraphrases, such as Grosser Gott, would be subject to the same rule, they being substitutes for or literary equivalents of Te Deum.

'Holy God..' certainly isn't Te Deum, but it seems to me that, as we all know, since it is a vernacular paraphrase of the same, singing it when Te Deum is dis-allowed is sort of cheating, creating a handy loophole. One cannot say that it's forbidden, but one can say that singing it is sort of slipping Te Deum in on the sly. Would we say that a vernacular paraphrase of Gloria was permissible at OF mass, or even as an offertory anthem, during Lent? I think all could see that this would be bare-faced adolescent tom-foolery. One has to wonder at the suspect motivation for even asking the question. It isn't mere words that are not allowed - it seems to me that honesty would be compelled to consent that it is their lack of penitential register and thrust as well.

I reviewed what Fortescue has to say and am, until someone offers evidence to the contrary, satisfied that the mind of the Church is that Benediction always have a festive, never a penitential, character.

It's well known that the alleluia is entirely suppressed in the so-called extraordinary form of the Roman rite from Septuagesima until the Easter Vigil. This rule admits of no exceptions whatsoever. Not so for the Te Deum even at Matins, which is required on the feast of the Annunciation, for example. The liturgical legislation of the Catholic Church stipulates that

the playing of the organ, and all other instruments is forbidden for liturgical
functions, except Benediction, during the following times:
a) Advent, from first Vespers of the first Sunday of Advent until None of the Vigil of Christmas;
b) Lent and Passiontide, from Matins of Ash Wednesday until the hymn Gloria in excelsis Deo in the Solemn Mass of the Easter Vigil;
c) the September Ember days if the ferial Mass and Office are celebrated;
d) in all Offices and Masses of the Dead. (De musica sacra, 80-81)

Perhaps you would like to enlighten us as to why the exception is made for Benediction, if not to emphasize its festive character. Would your "common sense" not indicate that such festive use of the organ is unseemly on a penitential day?

Whether you personally agree or not, Benediction is "more privileged than Mass itself in these regards," as the document cited above clearly demonstrates. You should think twice before accusing other forum members of cobbling together their own notion of the "mind of the Church" to justify whatever you consider to be liturgical abuse, especially in the absence of specific rules. How patronizing!

As far as I'm aware, lace on paraments is a post-Counter-Reformation innovation, but that's another topic altogether.

N.B. the use of the organ is allowed at Mass on Gaudete and Laetare Sundays, but the Te Deum is not said on these days.

Glad this is all clear now....

From what I have read, the only music required by the rubrics are Tantum Ergo, and the Versicles and Oration (assuming they're sung), everything else falls under the all-encompassing heading of 'local custom'. Below, I reprint verbatim the directions for Benediction given in the New St. Basil Hymnal (1958).

+++++++++++++++++++++++++

BENEDICTION OF THE BLESSED SACRAMENT
(Simple-Solemn-Pontifical)



TANTUM ERGO immediately followed by the VERSICLE and RESPONSE:

V. Panem de caelo praestitisti eis (Alleluia).*
R. Omne delectamentum in se habentem (Alleluia).*

Then the ORATION, sung by the priest, with the choir's AMEN.



The above are the only musical requirements of Benediction. It is customary to precede these with the O salutaris Hostia or some other hymn in honor of the Blessed Sacrament, either in Latin or in English. Hymns in honor of Our Lady or of the Saints, as well as hymns of the season may also be used.

If the Te Deum is sung, it must precede the Tantum ergo, and it must be sung in its entirety and in Latin.

Between the oration and the blessing with the Blessed Sacrament, nothing may be sung. During the actually blessing nothing is sung, but the organ may be played softly. Present day custom has the blessing in silence, except for the altar bell.

The service is frequently concluded with the antiphon Adoremus in aeternum and Psalm 116, Laudate Dominum, or with Holy God, we praise Thy Name. An English or Latin hymn of the season may replace these if desired. (Also see pages 130-131 for additional antiphons to be substituted for the Adoremus in aeternum.)

* The Alleluias are added only in Paschal Time and on the Feast of Corpus Christi.

Cantus Selecti is good. We use it for the Tu es Petrus and prayer for the bishop, with the verse and collect following as well as te hymn at the beginning, the concluding invocation to the Sacred Heart, and the Tantum Ergo.