I checked Yaretzi a while ago for my own database and didn't find a good source that confirms the meaning of "you are beloved" (or any other meaning). Unfortunately it does not mean much to find info like that in many places all over the Internet because there is so much copying going on.
Regarding Nahuatl I found this however:http://ancientscripts.livejournal.com/100602.html?thread=354554
See the posting and the answer at the end of this article about Nahuatl: That language has no "r" sound, so a name like Yaretzi as Nahuatl does not fly.
That let me personally doubt "you are beloved" as well.