I took a quick look and yes the slime scene was missing a line to erase that picture. It's been fixed in 1.2 which I hope to have up later today.
The help option goes silent during the mansion because I wanted it to be more challenging, I can add a better help section for the mansion if needed.
The orb room, there is a panel on the northern wall that actives the puzzle. Once activated, you have to change them all to one color starting with red, then interact with the orb on the southern room that matches the color. You only need to do red and blue to progress, yellow and green are optional treasures. The item you get for completing that will let you complete the other rooms.
Yeah, the mansion is suppose to be the last area. Going back to the east and completing that would mess up the help system, I'll add a fix to that in 1.2.