I feel like it was easier to write for Black Butler (back when I was still actively writing it) as opposed to Twisted Wonderland.

Sure, it takes place in the late 18th century and there's a bunch I don't know about the time period such as etiquette, dressing, cuisine, history, politics, etc. but I think that was the beauty of it. Both the anime and manga were nonsensical in their own right, like the ice sculpture or curry contest episode. I know those ones get bad rep for being so out-there, but I think it was important to younger watchers and aspiring fanfic writers to see that the show and canon is not afraid to get silly and outlandish.

Write modern bathrooms, add proper plumbing and modern-day appliances, it really doesn't matter! Because in a world where chainsaws are wielded by badass genderqueer grim reapers, I don't think being entirely historically accurate matters too much. Not to say it doesn't matter, no, no, no. I always enjoy writing as close to canon as possible, that's how I indulge in fandom spaces. But with Black Butler, it's a bit difficult to know what exists and what doesn't, since it has such a blend of accuracy and a modern-spin.