I think the castle from the 12/17 video looks like the Shoei space from Japan. I thought I remembered it as a more vivid-looking space if I recall, so I could be wrong.
It's a different space. The Shoei Kingdom is more anime style, and bright white walls:
Shoei's Kingdom is my favourite space in JP. I really wish they would bring it to NA and EU. They update this space regularly and the sky changes every month. There's community tasks, mini games, rewards. It's just an all round fantastic space. The atmosphere there is fantastic and there's always something to do or see. I love it!
We've added a day/night cycle to the Dream Island, but I don't know when this update will be going live unfortunately, so it may be a few months away still. The reason for this is that we had something larger planned to release in conjunction with the Dream Island update, but that probably isn't happening now and therefore we're having to re-evaluate our plans.
I took out the pics in the OP that were identified.
This pic looks like it could be a Lockwood space....???
Tim never said what "something larger" was.