Oh ya, the double thread screws have to hand tightened by the post. There's no way for a wrench to tighten it.I did tighten every bolt very securely. If it has to be taken apart for a move, we're going to need to use a drill to do so because I am pretty good with tools.
My only concern is one that a guy couldn't have done much better on, and that's the bolts with the double thread. There isn't a tool out there that can tighten it, so I had to twist the support until it just didn't move anymore.
The reason the cat was unstable was not the joints. If you look at the platform that the second house sits on, you will see that it is L-shaped. When he was scratching the front sisal post, he got really into it, scooted back and very nearly stepped off the platform. When he felt his foot nearly go over the edge, that freaked him out and made him feel unsteady.
The platform at the second house is too narrow and not much standing space. My boy's old tree was the same, narrow boards. The new one I bought him was much broader and he has more space to stand.