Psh, thats only cause of some type of universal translator device. But as I have yet to see a Babel Fish in the series, (my personal favorite such device), I still hold that they do not speak English, Or latin. Personally I think they speak Aleran, a mongrel mix of Latin, French, German, Greek, and English. Because remember, these boys aren't from Rome per se.... they are just a Legion who got picked up and deposited in the back end of no where.