Wow, I have to give a big shout out to RKC. I messaged him and he gave me his number. Talked to him about this and several other mistakes my mechanics made for like 30+ minutes. Hell of a knowledgeable guy!
So here's what he taught me: The bolt is a carriage head bolt with the head down sandwiched between the top of the foot and the cap on top of the solid foot. The bottom nut should be tightened to keep the square of the carriage bolt in the plywood and stop it from turning. Essentially the square on mine must have gotten rounded out but you can still get it to stay if you tighten it down good.
The bottom nut must be tightened to the top of the foot to keep the bolt from turning and then you can adjust the top nut wherever you need to. It might also need to be lubricated if it's won't turn freely according to RKC.
Knowing this, I would say the middle washer is completely useless, as it just sits on top of the bottom nut and serves to confuse people.