I'd be very surprised if they didn't have at least one test server, especially since they had one with FF XI (called Atomos). I did some Googling and it suggests that they have at least two test servers for FFXIV, Narshe and Zvahl, although that might just be for 1.0. Just because they don't show us the names of them, doesn't mean they don't exist (it's probably less confusing to not show us since we don't really need to know).