Can a believer, while in Paradise, ask Allah Almighty about unseen matters of which he was unaware in this world, such as the substance from which the soul was created, or where Allah was before the creation of the universe, and what He was doing?

There is no certainty regarding the persistence of "cognitive anxiety" in Paradise, or whether it will be a delight sought by its inhabitants. However, if Allah wills its persistence as a delight, then there is nothing to prevent such questions from being raised and answered, for Paradise contains everything the souls desire, whether sensory pleasures or intellectual and spiritual knowledge, as Allah the Almighty said: (And therein is whatever your souls desire, and therein is whatever you request). The texts have indicated the fulfillment of everything the believer requests, even if it pertains to worldly matters, such as planting or having offspring. What is important in this world is to engage in righteous deeds and not delve into the unseen without lawful evidence.