When I made the last post, I forgot to add the text of the song and I made a (not perfect, but approximative) translation of the words.
Congaueant catholici
Letentur cives celici
Die ista
(May celebrate the christian people and may rejoyce the beings (citizens) of the heavens today.)
Clerus pulcris carminibus
Studeat atque cantibus
Die ista
(May the clerics make an effort (to perform) beautiful chants and songs, today)
Hec est dies laudabilis
Divina luce nobilis
Die ista
(This is the praiseworthy and glorious day of the divine light, today.)
Qua Jacobus palacia
Ascendit ad celestia
Die ista.
(As Jacobus is resurrected to the palace in heaven, today.)
Vincens Herodis gladium
Accepit vita bravium
Die ista
(Defeating the sword of Herodes, he wins the prize of life, today.)
Ergo carenti termino
Benedicamus domino
Die ista
Deo dicamus gratia
(Therefore let us praise the lord incessantly, today. Let’s give thank to God.)
The performers of the song are members of the Ensemble für frühe Musik, Augsburg. Unfortunately,
their webpage is only German.
I also found this short article on the subject:
The Codex Calixtinus and the development of polyphony in the twelfth century x-posted in my journal,
middle_ages and
historyisfun.