I am from Malayalam wiki (http://ml.wikipedia.org/).
Currently in local wikis we have the option to set the prefered langauage to English . Once we do this all the messages will be in the language that we selected.
Like the same way is there is any way to set the preferred name space language to English. That is when we select the preferred langauage as English all the name spaces should be in English.
Recently we have converted the name spaces in malayalam wiki to malayalam. But this is creating lot of problem with non articles. (Eg:Templates, Category and so on).
The main problem is that the url that we copy from the browser is percentage encoded. Because of this we cannot use percentage encoded url(or the url that has local language in address) in our communication. Example : send the percentage encoded url through email, gtalk and so on.
It will be good if there is an option to set the prefered name space langauage also to english. I think this will be a problem for all nonlatin langauage wikis.