For all intents, Superman was dead. Very dead. It was made explicitly clear in the Death/Funeral/Return storyarc that he was dead.
I'm sorry, but if that story also established that he would have regenerated on his own
so long as he got sunlight, then that's just not compatible with saying he was dead. If the intent of the story was that he was decidedly dead, then the story should not have claimed he would eventually recover on his own, because anything you can recover from is, by definition, not death
So it sounds like the original story was trying to have it both ways, and I don't buy that. It's sloppy writing. And actions speak louder than words. No matter how many times the story said
he was dead, if the same story also established that he was capable of recovering on his own, then he wasn't truly dead. And if he was truly dead, then he shouldn't have been capable of recovering on his own. It's as simple as that. The very definition of mortality is that it is not spontaneously reversible.