No. It is not the fact that Leadville is far away that seems unreal; it is Leadville itself. The burrow is so far from Leadville that anyone in the burrow will imagine that Leadville might not even exist. From the parental burrow, Leadville seemed so far away that [Leadville] was only half real." This is what Bruce was getting at with his example, but I wanted you to see why your suggestion wasn't the same in meaning.

It's more two seems: It seemed so far away, that it seemed half real.

I think you are correct Ruby, but I would change your sentence slightly to read this way: "Leadville seemed so far away from the parental burrow that it was only half real."