The problem is the bishop's parts, if I understood correctly. Recto tono is always OK for the collects. Otherwise, the tone as for the Asperges, the Marian antiphons, Benediction (customarily, "Oremus" ends with a minor third, the collect with a descending fifth, similarly to the prophecy tone's sentences, and then the conclusion with a minor third again).

Versicles and responses are always concluded on a minor third. Dactyls customarily sung with the drop on both the second and third syllable, Hebrew word and monosyllabes as if it were an ordinary Latin word; the alternative formula is too hard). Dactyls include words like "fortitúdinis" by the way, since with the accent the word is accent-weak-weak in a group of three as far as applying the tone goes.

All of that is in the Common Tones of the Mass/of the Office in the Liber Usualis.

I would check to see with Canon Avis of the ICRSP (he's the American provincial MC and has long had to travel for confirmations) to see if they have music for the prayer that specifically prays for the gifts of the Holy Spirit. I cannot remember if the metrum is used or if it ends with a minor third, on a flex, like the versicle tone above, and I'm not gonna trust video, unfortunately, because a lot of clerics do one or the other not understanding the difference, though it's not a big deal for the response. You can check with him, but my understanding and what I would do on the spot is that the Amen is recto tono.

If you need a new score and want some help to make a score, we just need a good clean PDF of the text so that we can copy and paste without much fuss.