there have never been a world 12 i think... if u look in the list its a lot of worlds that isn't there for example; world 15, 49, 50, 51, 52 and so on...
the following worlds isn't in that list because they are german worlds; 122, 139, 140, 146, 147... u can access them if u go to runescape hompage and select language 'Deutsch' to the left just under the runescape logo... but u will get everything in german if u go to one of those worlds so it might be kinda hard to understand... but its maybe good for autoing if those worlds maybe are kinda empty...
proboably many of u allready knew this...
EDIT: sadly u can't get on to the german worlds on rsbot :/ maybe something they should work on, since it isn't very few ppls on those...
ah no, world 12 had a very old server and thats why people had trouble dueling in it they have already taken it down twice but they're a bunch of jews. It may not be up for several months as they have no reason to rush it, people can simply play other worlds.