I can place a floor tile on top of the floor tiles I have up there, so yes allowed and I placed the corner Pillar and lowered, so that is allowed too. I also placed the walls on a block and then lowered them, they did not go back in my backpack, so seem ok.
I did not raise them higher than allowed, I tryed to raise floor tiles 2 more, but only one more is allowed. Think K fixed it so you can't raise them to high.
I believe only the 2 floor tiles are an issue, as they will show, after I visite my neighbors castle, the first one North do not show so if K will fix the floor tiles, that are stubborn, I think it should be ok as long I don't place vendors or other stuff, that will be visible after I visite my neighbors castle, I believe it should be ok.
I look forward to see if it's still there, when I get home from work, I hope it is