Lasso - Falsobordone

I am trying to introduce Falsobordone (Fauxbourdon) to my choir at our Extraordinary Form Mass. Having read a forum post about Lasso's Falsobordone, I went to the music library at my local university and found his settings in his complete works.

The Falsobordone are listed my Primi Toni, Secundo Toni etc. I expected these to line up with the 8 modes but it appears they do not.

What am I missing?

I have attached the First Lasso Tone as well as my pointing of the text. I took the Mode I Psalm tone from the 23rd Sunday After Pentecost Communion Proper. My intention is to set the lesser Doxologies to the falsobordone as a way to introduce this to the choir.

Thanks for the help.
J