[Quoted from a forum post by Mason Fisher, composer of the game's music]
The vocalists name is Toni Burdey. She is a wonderful talent! When I worked with her to add the lyrics to the melodies I composed for the intro movie, it was more important that the lyrics matched the existing melodies and were "singable." We took MANY liberties with the phrases to make them work musically. So, the lyrics are short Latin phrases that are somewhat organized as far as meaning and content.
The language is Latin. Here is a VERY rough translation for the intro movie. Again, many liberties with the language are taken here.
et behl-luum In i tehr-nuum
Doo-kit ah-mawr Pah-tree
day-baw-noh- et mah-loh
A hunger that leads to crime and war...forever.
From effect to cause...woe to the vanquished by force of arms.
The final argument...your death.
Love of country guides me for glory
come what may...know thyself...always on the ready....truth.