Which means that once you get back to the Latin of the Late Middle Ages, you need to go to the Latin of the Early Middle Ages, and then the Latin of the Late Roman Period ~ or maybe the Middle Byzantine Period ~ or maybe even to Modern, Medieval, Byzantine, or possibly even Classical Greek (depending on phrase or clause at dispute, and when it originated, and which authorities of which rank and reputation ever commented on it).
In general it's usually more efficient to simply come up with a more modern statement than to try to figure out what a writer/source/authority meant more than a thousand years back.
There are people who despise modernism but that's a whole 'nuther question.
With several years of Latin under my belt and a thorough grounding in Spanish, French, German, Italian and several other languages, I couldn't quite figure out what the translating authority had done by simply leaving the spiritu part out. Left me feeling I must have missed class one time too many or something.
“I couldn’t quite figure out what the translating authority had done by simply leaving the spiritu part out.”
Theory: what if the folks coming up with the English translation were trying to produce a liturgy that did not sound like the 1662 or 1928 Book of Common Prayer (both of which use “and with you spirit”)? Otherwise they’d be accused of pirating Anglican liturgy.