These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Basically, the only thing keeping them from being "official" official is that it hasn't been explicitly stated (Maya's above comment notwithstanding). It's all there on the screen, it's just lacking the words.
Rewatch Bonus: The first 10 episodes are intentionally designed to let the viewer know only as much about what's going on as Kazuki does, which amounts to about jack shit (and is the reason those episodes aren't considered very interesting to watch your first time through). Second time through the series, there are tons of little things that make complete sense now that you understand the nature of the Festum.
What Do You Mean, It's Not Symbolic?: Tatsumiya Island uses a lot of Norse mythology for its suit and weapons nomenclature, including the eponymous Fafner, Lindwurm, Fenrir, and Garm, but it's also perfectly willing to borrow from Greek (Medusa, Aegis, Titan), French (Durandal), and Hebrew (Solomon). The UN variants are named for the Greek words Megatherion (Great beast) and Gnosis (revealed knowledge), and the city of Babylon. The Festum cores are named Mir (Russian for peace/world).