[Skarg]

Well the spell from Interplay Summon Spican Stardog wouldn't work... but we didn't use that anyway.

And what about the effect on astrology? Maybe everyone lacks personality, or has similar personality traits due to the lack of star signs. Or perhaps they do, but astrology doesn't exist. Or maybe astrology is known, but people think stars are just something an astrologer needs to see with their third eye. Or...

More seriously, perhaps the M'noren who created the world don't mind that it's hard to navigate there. Maybe they prefer that. As a GM, I tend to enjoy differences between places and elaborating on their effects. More difficult navigation and mapping sound like a perk to me rather than something I'd necessarily want to undo and return to "normal".

But again on the "planet-scale engineering is an extreme ability, especially to actually do rather than just theoretically be able to do", it seems to me that if the M'noren can really construct a world in the first place, and bothered to do so, with some sort of planar barrier all around it, no less, then arranging for lights in the sky would seem well within their means. After all, even insanely terrible 20th Century corporatist thinkers suggested advertising in the sky. If the stars were night-light satellites, then that would also tend to mean they could be arranged in whatever constellations and interesting movements the M'noren wanted. It could be pretty useful for claiming you were godlike if you could predict and cause the stars to do things!