I'm of the opinion that only the Scions and Echo-users are aware of Hydaelyn's role as the Mother Crystal.

As far as common Eorzeans are concerned, the pantheon they're familiar with is that of the Twelve. I don't recall any scene, quest (MSQ or otherwise) or side-story where an NPC specifically "worships" Hydaelyn, or "believes" in Her existence.

Similary, ordinary Othardians have their own pantheon. They believe in the kami. And again, I have yet to come across any evidence showing that they're aware of a Mother Crystal.

Echo visions, or any other manifestation of the Echo, would be seen as an abnormality, maybe as a gift, maybe as a curse. But unless the Echo-gifted individual meets the Scions, or perhaps some other Sharlayan scholar who is in the know, it's unlikely that the individual, Eorzean or Othardian, would independently figure out the source of the Echo on his or her own.