I wondered if the Palmer-Burgess Gradual had a version of Petite in it and how it might turn out in English. Sure enough, it appears, and it preserves the structure of the Latin! How it might turn out in modern American English is another question.
Ask Ye, Communion chant in English
Very apt and nice, and I don't think it poses any material obstacle to intelligibility (which I distinguish from immediate comprehensibility).
I represent the opportunist perspective when it comes to use of older English idioms. That is, I don't value consistency in the usage as such – because English is, idiomatically, a language that does not reveal logical consistency to be one of its chief characteristics.
Anyway, I've generally looked askance at updating "archaic" usage in texts that were written before the advent of broadcast media, except where a word's meaning has become sufficiently changed or obscured that it is prissy to retain it rather than change it.
On the other hand, I do find composing new texts employing that usage to run the risk of being gimmicky and over self-conscious – it reeks of the Aesthete (which is very modern, not very traditional).
All that said, there are aspects of the older usage that are still useful – not only as demonstrated in this vernacular chant setting, but also because "Thee" offers a lot more terminal rhyming combinations that "You", even in with English's ginormous vocabulary.
I feel most comfortable when it seems people are free to toggle in usage for expressive spaciousness, so long as it doesn't reek of the Aesthete or that hobgoblin of foolish consistency.
End of ramble. Nice job, again; it's an attractive setting.
It occurs to me to briefly elaborate on something I alluded to above: the shift in perspective on usage with regard to the advent of broadcast media.
I guess it's a shift back to orality (and therefore greater correspondence with the loops and eddies of the river of the living language) away from The Book (and by this I don't mean the Bible, but The Printed Word as primary medium of communication standards) that obtained – rather artificially – for a few hundreds years beforehand.
Virtually no one pays attention to this issue, and paying more attention to it might illuminate some of the tensions between expectations about language that we are witnessing. Anyway, it's just a thought.
In the original Latin version you find that certain words have been stressed with melismas normally on their accents, a sort of rhetorical device used to highlight the musical text because of their importance for the composer usually for the textual message. Here, in the original Latin, pulsate/pulsanti and invenientis/invenit are highlighted, creating a sort of theological summary of the text through music that says "When you knock on God's door you will find behind there what you are looking for". This is very important here because these communion antiphons were used as processional antiphons during communion, and those two words just stand out for the communicants to hear. I need not mention the implication of how the door to heaven has been opened by Christ, here sacrificed on the altar of the sanctuary, and the communicants can find Him as the Bread that they are receiving, even though He has ascended into heaven, a feast for which, in the old calendar, followed the Mass with this antiphon, the minor rogation days.
The English Palmer-Burgess was able to keep the knocking part as highlighted, but because the future in English requires an auxiliary verb, "will" or "shall", the word "find" could not be highlighted and it is merely the banal auxiliary that becomes highlighted, the "shall". These sorts of English adaptations of the Gregorian seem to put the music ahead of the text, and as a consequence you may loose some very important musical commentary on the text that is found in the original.