Copied Factory

[Nestama]

I actually asked myself a similar question; how did they not see all that? They have Amaro. Eulmore, a military power who would most definitely patrol their borders, has airships. Kholusia is SW of the rest of Norvrandt. It would have been literally impossible for everyone to have missed everything that was in that valley from the sky.

It's called the Copied Factory, which has me believe that everything behind the door the two dwarves blew up is all artificial, the sky included. Basically, it's all underground.
Why NieR stuff is in FFXIV can also be explained via one of NieR: Automata's endings, too. Wouldn't be the first time Yoko Taro used an ending of one game (Drakengard's E ending, where Caim and the Red Dragon end up in Tokyo) to start a new story (NieR)... the real question is how it ended up on a Shard, though.