I forgot to mention, another problem is that you can't even import Wikipedia: namespace pages to your wiki without changing your interwiki table to get rid of the wikipedia: interwiki prefix first. The importer will say, "Page 'Wikipedia:Sandbox' is not imported because its name is reserved for external linking (interwiki)." As I notedhttps://bugzilla.wikimedia.org/show_bug.cgi?id=60168#c2in bug 60168, it's unclear why we would standardize the other namespace names (Help:, Template:, MediaWiki:, User:, etc.) from one wiki to the next, but not Project: