@BugDemon -
You wrote:
"The main message, as far as I can tell at least, is to form connections and find compromises. The idea of bridging the gap between light and dark is certainly the main plot point, but that also reflects on the message. Working together leads to better results, being kind to your enemies and friends leads to a peaceful and happy city. Finding compromises and complementing each other's strengths will lead to the best outcome."
That's fair. And it's set in the context of a war that's been going on for thousands of years where every victory is a defeat, in terms of a global outcome, so the solution you describe is necessary to call the whole thing to the halt.
I have no idea how applicable this might be, but I spent some time studying and doing scholarship on ancient civilizations in the Mideast and this author, intentionally or not, casts some interesting light on the whole business. Lilith goes all the way back to Sumer, but she's best known as a Babylonian demon. The Old Testament has a particular slant on that time, but enough to show that it was a savagely difficult world these demons and angels started fighting in. Demons and supernatural tricksters were conceived and feared for some very good reasons, and the deities were scary as hell.
But in this series the war is over except for the winning side stopping just short of genocide with the losers. It's not that the angels/magical girls are bad or that the demons are harmless, but that this late in the game, it's time to call the war off. And what you described is how this series prescribes that.
Sakura definitely has her problems and has made more than her share of goofy decisions, but she does have an extremely sharp and knowing perspective on how to save that town and keep it safe. The fact that she gave the charge to a demon who she helped save by giving up her core to that demon, and the fact that she can imagine a demon taking care of her beloved magical girl sister, puts her in a strong position of authority, I think. She represents the attitude required for what you described.
Shamiko may be what the whole business depends on, But Sakura delegated that responsibility with great wisdom.
It's a great series, a real joy. There's no doubt that the war will end. But even though I only know a bit of what's coming, it's clear that the peace will not be easily purchased.
(And what terrifying force almost beat Sakura and Joshua and reduced them? Damn. I have a guess, but it's enough to make one's hair stand on end.)