I'm not sure how to feel about the other moons. First, this goes back to my not liking that Etheirys has no natural moons. Second, the moon serving as a prison for Zodiark/spaceship means it didn't exist until after the sundering, so all of the moons for the shards should be 'new' too. Third, I'd say maybe this'll finally address whether or not Hydaelyn was sundered, but I'm hoping we're done with her.

We know that the shards are 1) in their own dimension and 2) their fate is tied to the Source, so their moons shouldn't be escape pods. They could have been housing Zodiark body parts, which is odd unless Hydaelyn repurposed an already existing satellite and fought Zodiark there. Otherwise, 14 moons would've had to have been created and Zodiark's body parts hauled to them. Did they set the stage for this?

Based on what we've been presented with in game so far I have no idea what purpose the shard moons could possibly serve and after the writing in EW I'm concerned it's going to be something nonsensical. Particularly with them wanting to be done with the arc of the Ancients, I can't even speculate that they'll have any meaningful lore.