This is a corrected version of lyrics I found at a Steeleye Span Web site; and it also corrects one word from the database, so now it makes a little more sense. I still haven't figured out a good translation. I'm not sure what the "mist takes a morning path" quote is, but it's not a translation. Apparently, Steeleye Span used the original tune from Piae Cantiones. The original tune is also supposed to be in the Oxford Book of Carols, if anybody happens to have access to that.
-Joe Offer-
Gaudete
Mist takes the morning path to wreath the willows - Rejoice, rejoice - small birds sing as the early rising monk takes to his sandals - Christ is born of the Virgin Mary - cloistered, the Benedictine dawn threads timelessly the needles eye - rejoice.
GAUDETE
Gaudete, gaudete Christus est natus
Ex Maria virgine, gaudete.Tempus ad est gratiae hoc quod optabamus,
Carmina laetitiae devote redamus.Deus homo factus est naturam erante,
Mundos renovatus est a Christo regnante.Ezecheelis porta clausa per transitor
Unde lux est orta sallus invenitor.Ergo nostra contio psallat jam in lustro,
Benedicat domino sallus regi nostro.