One of the things that makes me believe there is echo outside of Eorzea is the very first time you meet Hydaelyn. You see many people circling the Mothercrystal, and they have said these are other agents working for her. Since having the echo seems usually a prerequisite to seeing her like that and we aren't literally tripping over hundreds of her agents, I would expect she has them across the world. Certainly it would be strange for her to localise her influence to Eorzea only since the Ascians certainly aren't similarly limited.