Hm, I think there might be a WOJ about the trilogy that you can kinda get a hint of the order of the trilogy. I think Hell's Bell's involves stealing literal bells. My guess is this is what kicks it all off and it'll involve Nicky and the Nickleheads and I imagine a few characters die. Hopefully not Michael, but if he dies it'll be during the trilogy.
With Empty Night, that sounds like it'll be the darkest hour portion of the story, which is usually in the middle, so this could be the second book. There's probably also a huge reveal about the universe in here and that it effects Harry greatly. So this would be the wham episode. More people die.
Stars and Stones reminds me of the words Mab said to Harry in Small Favor in the church scene. So that could be foreshadowing something going on with Mab and where the fae hand the reins over to humanity when it comes to protecting the Outer Gates. This is when people really come together to stop the Outsiders. The nature of magic changes in a big way b/c of the influx of humanity knowing about the supernatural. Molly could become the winter queen or revert to human or become something else entirely.
