I will echo Ildur and FW on this one. There is no indication anywhere that any languages exist in Eorzea other than the common tongue. Different regions are likely to use the language in slightly different ways and accents probably wouldn't be uncommon. Even within the United States, there are accents varying by where people live and different words are used to describe items. Soda or pop, for example. The only other language we see an example of is Roegadyn and even then we only have a smattering of words with no indication as to how those words would actually be used to form complete sentences.
