I think a lot about the connection between otherworlds and the ethnic maps of this world, and whether on the edges of our ethnic maps, those otherworlds mix, and how well they do it--or don't do it.

I think I concluded that otherworlds travel with the travels of people in this world--I think.

Regarding people's interactions with the otherworld(s), I do think strength-of-wanting can make some things happen; it works in this world after all, sometimes (though very definitely not others). If you want to sing a golems into being, and work hard enough at it, I'm sure you will. In fact, I imagine there are quite a few out there already that you've created, and you just aren't aware of where they've gotten to.