Everybody needs a lazy day now and then! I agree there's more positive body language with Cinder. Also, they were sitting fairly close without any overt attacks. This is encouraging but I don't think they're ready to spend a whole night in a confined area yet.
There does appear to be progress with Cinder being more comfortable. Good luck, hope they can bond somewhat, and keep each other company even if they don't become close. But who knows, unexpected things happen sometimes. Calico Lucy is my problem child. She really should and would much prefer to be in a single cat household. She's sweet as pecan pie to me and other humans but she’s a trouble-maker to the other cats, socially awkward, distrusts them all. She acts like they’re attacking her when they’re just playing, its like she's never been around other cats before or maybe was bullied by one before, for some reason she just doesn't recognize play behavior. I adopted her from a rescue through their PetSmart program and the description specifically said she liked other cats, but she was the only one in the front display area, and I ignored my inner warning about that. She and my three other cats would have all been happier if she'd found a home as the single cat. We don't have actual fights but when one of the others even walks too close she lays back and lets out yowls like she's being attacked. It's been a year since I brought her home and no change on that. She used to try keeping Sophie out of the litter box and attack her when she was coming out of it, and I've greatly reduced that by doing guard duty for Sophie and moving the litter box from the laundry room to the craft room where I spend more time. Sophie has adjusted her schedule to go when I'm usually there, too. I've able to reduce her stalking them by being watchful and stepping between her and the others and saying "No! Walk away." very forcefully. Now when I say walk away she'll stop and look at me so it serves the purpose. Thankfully I've never had to actually separate any real fights. She still chases Sophie for some reason, if Sophie walks by when she's hidden and can do the ambush thing.