I say give it a shot, at least a portion of what you have in mind. I'm sure plenty of us would be interested to see a different approach to this hell of a mess of a story.
Okay.
Most of my thoughts so far have been regarding heaven, as I'm really not a fan of how Heaven was portrayed in the show in terms of it's denizens (Adam) or the way it looks. Heaven shouldn't look like just another regular city, it should be an entirely different kind of civilization alltogether, with it's own constructions, infrastructure, way of life, and more. it shouldn't look anything like hell. The way the show presents it makes comparing heaven and hell look like comparing California and New York, which just isn't how an otherworldly civilization built on virtues and faith should look like.
Secondly, Adam. Here's how I would rewrite him and some events surrounding him because I do not like how he's written or portrayed in the show.
So Adam was there with Eve when they got kicked out of Heaven right? he wandered the lands forever guilty of his inability to stop Eve from breaking the one rule God had set for them. Eventually he would die, and where would he end up? hell. Adam wasn't a bad person, but because he was banished from the Garden of Eden by God himself, he wasn't able to go to heaven. He fell into hell and saw Hell in a more primitive state, Lucifer was still developing his Palace with Lilith and the entire systems of hell had not been established. Lucifer was thrilled to have Adam with him, it meant there was going to be more, more sinners, more inhabitants, he could have the world he wanted, he could truly be a ruler. However Adam and Lucifer had two very different ideas on what hell should be like, to Lucifer, hell should be it's own crooked paradise, a place where people sent to hell could indulge in all of the sin they wanted forever instead of be punished for their wrong-doings. Adam however had a different idea in mind, he wanted hell to be an eternal punishment for sinners, or at the very least, a place where they are doomed to wander as he did, he still felt incredibly guilty and never really agreed or followed in Lucifers footsteps, he knew he was bad, and he knew the people arriving down here would be just as bad if not worse, and he didn't want them to indulge, but rather to repent. (This is meant to address the criticism of hell in the show not really being a hell, rather a kind of sandbox paradise for it's sinners, the reason it's like that is because Lucifer himself built it that way, he's Lucifer. He's got an ego, why should he punish the souls who fell down here? why should he do what God and his butt-buddies supposedly wanted? God had banished him, stripped him of his wings simply for daring to question him and try something new, why should he adhere to what they want?)
Despite these differences, Adam would stay by Lucifers and Lilliths side, attempting in vain to convince him to do things his way, Lucifer never got rid of him because having someone who had directly interacted with god and had invaluable insight was simply too important of a person to disregard, and it stayed that way up until a long while later, at this point Pentagram city was being developed, and far more people had fallen into hell and were helping build it, the systems and hierarchies of hell were being built and sin ran rampant. Adam still tried to convince Lucifer, offering a compromise of entrapping people who had done particularly awful acts into a dungeon, Lucifer said he would consider it, but every time Adam inquired, he said he was still thinking about it. Fast-forward another long while later and Pentagram city is "thriving", and Adam was distraught. He thought that, despite his grievances, perhaps some sinners and some fallen would feel the same regret and guilt he did, that it was possible that he wouldn't be alone, but once he took a good look at the city, he knew he was so dearly wrong. Even the people who did genuinely feel guilty for their actions and wanted to repent were typically beaten in the streets, their skulls smashed open and killed over and over again until they just stopped appearing (for context, in this rewrite, you can die and come back in hell, but you get just a bit weaker every time you die, whether it be your mind, your skin, your flesh or your blood. You get a tad bit slower, you can't remember things how you used to, you aren't as smart as you used to be, your magic/muscles are a bit weaker, stuff like that. Once you die enough times, you enter Limbo, which is an entirely different thing I'll save for another time)
Adam, finally fed up with this, went up to Lucifer and his council ( the seven deadly sins, who I haven't fully thought out yet but what I'm going with now is they're basically incarnations of mankinds worst aspects come to life) and had a massive argument with them, saying that if he didn't start punishing the sinners, he would start punishing them, and for every sinner he punished, he would carve a piece of flesh off himself and force-feed it to the sinners, forcing them to eat their well-earned retribution physically and mentally. after the confrontation grew physical, Lucifer entrapped him in a stone dungeon at the very bottom of his palace, just like he always wanted. Adam is kept here, being tortured in all kinds of brutal and awful ways, barely fed, barely watered, alone, at the bottom of hell.
Fast forward to when Jesus sacrifices himself for his sins, I don't think this would bring all of the sinners down from hell into heaven, however the one man that would be saved from eternal agony was Adam. God himself interfered, offering Adam a way to rejoin his kingdom up above, Adam was confused, and initially refused, still feeling he was guilty, however as he was weeping for his existance, he closed his eyes, and found himself in Heaven with a new body, a towering body, atleast 12 inches tall, with 2 sets of arms, 4 wings, and one eye in the middle of his head, he was able to speak without a mouth, able to hear without ears, and able to cry without tearducts. He thanked God, he thanked and thanked and thanked him, accepting his new position as an Arch-angel with a promise of redemption and honor, cementing himself as one of Gods closest Angels.
THIS. Is why Adam doesn't believe in redemption, it's not that he doesn't want to, it's because he's SEEN hell himself, and what Lucifer has turned it into, and that was Hundreds of centuries ago, he KNOWS how corrupt hell is and what happens to the actual remorseful people, he's SEEN how people indulge in sin, he's been at Lucifers side himself and saw what he turned hell into, he was there for all of it. And if it was that bad back then, who knows how bad it is now, it's a place of sin, a place of unrepentance, and a place, of hell.
However, Adam offers Charlie an olive branch. You see, over the endless amount of time Heaven and Hell have been things, there HAVE been some fallen angels, they are few and far between, but they do exist. These angels are escorted down into hell in secret for fear of them being instantly cannibalized if it were known that they were angels, and it's treated as a tragedy when it happens. Adam thinks of his fallen bretheren with sorrow, knowing where they ended up, and turns to Charlie and offers her a chance to prove herself, if she can find one, just one, singular fallen angel, bring them to the hotel, and properly, 100%, rehabilitates them, he will consider taking it up with the council. Adam knows it's a long shot, after all, if they could not be helped in gods kingdom, a place that rewards virtues, how could they hope to get better or redeem themselves in a place that actively harbors and encourages sin? Despite this, he doesn't want to shoot down the idea, he can see that Charlie is nothing like her father, he can see the genuine optimism and glee, an optimism he wishes he could have experienced for himself, so he offers this one chance at true redemption. he WANTS it to happen, but he just doesn't think it can. Adam gives Charlie a list of fallen angels, what they last looked like, and where they were dropped off, and bids her farewell, hoping for the best, but expecting the worst.
What do you think? Do you like it?