What about setting it during a story with a linear timeline rather than a "Day in the life of" game?
Rather than "It's Carnival Row!" as the driving force, why not focus on a linear story in which the characters could bind together on and keep driving the story? Like the invasion of Tir-Na-Noc or another island similar to Tir-Na-Noc?
Sounds like a win to me. You get The Greatest Generation crowd hungry for quasi-Victorian World War 1 action, and you get the Fae Rpers hungry for a fae game.
Pretty sure someone would love to play stuff like a flying pix runner scout during trench warfare or a satyr-type fae diplomat trying to woo human lands to join them in the fight. You could leave TirNaNoc alone and run parallel to the show without being slaved to what happens on TV, but evolve the game based on the events of the show.
Edit: Oh, you could also then allow human characters in the form of sympathetic humans who emigrated to the island to help in the fight. Stuff like chaplains, soldiers, war profiteers, weapons runners, lovers, God-children to pixies, people bound to join by prophecy or promise...