Why some quotes of him make it feel like he can't make stars anymore, like " Feels good to make things again " and " I grieve for every star never born " ? He is a slave of the targonians , but he doesn't stay on earth all the time. Why can't him make stars so?
It's not that he can't make stars anymore, it's that Targon doesn't really give him the leeway to do so.
In his lore it says that
As his past glories slowly vanished from the celestial realm for lack of maintenance, Aurelion Sol resigned himself to never again bask in the warmth of a freshly ignited star.
Basically aurelion thinks that he isn't worthy of creating new stars after he caused the destruction of so many already. And the crown forces him to obey targon,which likely means he doesn't have the time to maintain all his stars.
