I think we should see Eorzea as Ancient Greece: Some of the greek city-states had their own version of the greek language, but they all were so similar that it was basically the same, with some small differences that wouldn't be worth representing in roleplay. Except for pirate speak, I guess, because pirates!
The Lalafell Naming Conventons mentions an anomaly in some of the male names, caused by a sound that is no longer represented in the modern language. So that means lalas, Miqo'te and Roegadyn has their own languages at some point in the past.
The Lalafell Naming Conventons mentions an anomaly in some of the male names, caused by a sound that is no longer represented in the modern language. So that means lalas, Miqo'te and Roegadyn has their own languages at some point in the past.