"This page is assuming a one wiki model for simplicity's sake."
That is just wrong. The wikis need different policies for undelete pages, at least, and coming up with one policy to deal with that for all of them is probably impossible since they have different liability. So it is liability that is going to define which wikis and how many exist.
Since area is one of the factors in liability (what is against the law to say where) that has to be the issue. But there is no problem with language versus liability, the choices are fairly obvious.