I have no idea how visions of a almighty god works but moses was in hell when jesus did the transfiguration , jesus does not have the keys to hell before he died on the cross , there for the transfiguration has to be a future event
I am he that liveth, and was dead; and, behold, I am alive for evermore, Amen; and have the keys of hell and of death.
9And as they came down from the mountain, Jesus charged them, saying, Tell the vision to no man, until the Son of man be risen again from the dead.
moses dead and burried
o Moses the servant of the LORD died there in the land of Moab, according to the word of the LORD. 6And he buried him in a valley in the land of Moab, over against Bethpeor: but no man knoweth of his sepulchre unto this day.
eliah however was picked up in to heaven just like enoch , moses did not he is sleeping but according the eternal soul doctrine he should be in hell in the time of the transsfiguration , there for its impossible that it was happening in the present