Come on, guys, there are major major reasons Roshar can't possibly be a moon and one of the moons a gas giant. Think about it.
Nobody ever remarks on how one of the "moons" takes up a quarter of the visible sky?
Each moon is in the sky only once per day and moves across the sky in a couple to a few hours. What does that tell us about their orbits?
Could a gas giant be far enough away to look like a small moon, yet have this rapid of an apparent motion? (The answer is NO.)
That they're really fast/close, I would think. Perhaps unusually so...
You may not be aware, but Mars's moon Phobos orbits in less than 8 hours, and gets less than 6,000 km from Mars's surface.
Curses! Foiled again by SCIENCE!!!
Okay, so the orbits aren't magically augmented.
Still, that leaves us some information. The three moons are likely captured asteroids, then, rather than having split off from Roshar during its formation, Luna-style. Three captured asteroids at the same time in relatively stable, seemingly very close orbits... Anything significant in that, science people?
I expect the moons were put in their current orbits artificially, but by whom or what I do not know. On astronomical terms, these are not stable orbits, but astronomical terms means millions of years. A few thousand or even a few hundred thousand years are no problem.
By the way, I minored in astronomy while at the university, for expressly science fictional purposes.
Were the moons also artificially created, or were they originally formed naturally?
I don't know.