I (grudgingly) admit that in the long run Latin tags will be a better option than English. But I'm concerned that saying "Latin tags only" is going to hamstring our efforts to fully tag the questions that we get.
To put it simply: We need are going to need a lot more tags than the ones we have now. And if we say, "no new English tags," then many people won't be able to fully participate in that effort.
I'm more comfortable if we understand that the end goal is that all tags be in Latin, with English synonyms, but that we will achieve that goal through the combined efforts of those less comfortable with Latin (what's the Latin for enclitic, anyway?) who create tags in English, and those more comfortable with Latin, who kindly retag with the Latin version and synonymize.
And yes, we need synonyms. Lots and lots of them.