I have tried searching on this forum, on vatican.va and on google on this topic. I can't find specific information and am hoping someone can point me in the right direction. If this has already been discussed, please send a link. Thanks in advance.

I have heard for years that the Council of Trent codified the liturgy and that it lasted for 400 years. I heard it forbade the use of the vernacular. I heard that Palestrina's Missa Papae Marcelli "saved" sacred polyphony from being banned by Pope Marcellus II. I heard that the council permitted polyphony, so long as it was not profane or impure, and that the words are intelligible. I never questioned this information.

I recently had to start preparing a presentation on the development of sacred music, with a mind to convincing those in attendance that our choir's use of occasional chant and polyphony was not only legitimate, but preferred. So I started digging for quotes. I have the recent quotes from Sacrosanctum Concilium, ch 6, Musicam Sacram, Paul VI, John Paul II, and Benedict XVI. And I have pre-conciliar quotes from Musica Sacra, Mediator Dei, Divini Cultus, Tra le sollecitudini, and even Annus Qui. But I can't find strict documentation for the Decrees or Canons from the Council of Trent related to sacred music.
All references I've seen point to a Canon 8: "Everything should be regulated so that the Masses, whether they be celebrated with the plain voice or in song, with everything clearly and quickly executed, may reach the ears of the hearers and quietly penetrate their hearts” (Monson). The Council makes it known that if music is to be sung, it needs to be clear what the text is in one way or another. It continues, “In those Masses where measured music and organ are customary, nothing profane should be intermingled, but only hymns and divine praises. If something from the divine service is sung with the organ while the service proceeds, let if first be recited in a simple, clear voice…". There is also a pdf from a book by K.G. Fellerer, and he quotes A. Theiner. That translation is similar to that quoted above.

Is there a site where this Canon can be referenced in its entirety? Also, is there an official translation, or will I just have to take the Latin text and pass it through google translate?