Ran this as a one shot at my table and it was great! I set it on a hill overlooking Lake Onda, with Gatsby as a former Schleswig noble, and 'Daisy' as a vague eldritch being. Our Wretched Royal rode their horse through the whole house, it was all super provocative and the final battle was epically bloody!
My only critique is that a couple of the rooms (like the Guest Bedroom and both bathrooms) were a bit boring as-is. I added a torn up corpse of a priest of the basilisks in the GB where the players found a little lore hinting at 'Daisy' and the occult nature of the party. I put a random encounter in the small bathroom (it was the drug dealer, on the toilet).
I also hid a sneaky Blood Drenched Skeleton in the spa bathroom, in the tub which was full of blood instead of towels, so it jumped out at the players and attacked with a spiky loofah.
Everything else was true to your module and we loved it!