Note: The following topic is not about namespace names and not about names of special pages.

Vanilla Mediawiki UI strings contain hardcoded localised link targets. For example have a look at MediaWiki:Blockedtext (if you want to get all (?) affected messages grep for {{ns:project}} in the sources). Well again in monolingual wikis no problem. These linked pages are supposed to exist but now consider a multilingual wiki...

For example "Project:Administrateur" is linked in MediaWiki:Blockedtext/fr from vanilla Mediawiki. Imagine using someone French in a wiki with a non-french default language which is commonly the case in multilingual wikis such as Wikimedia Commons (note: French is just an example this holds for every of the zillions of languages supported by Mediawiki). So UI messages were created with monolingual wikis in mind and never considering simultanous usage of different languages.

So in vanilla Mediawiki please do not hardcode any wiki page in message strings.

Well how to localise embedded link targets in the future? Use a mechanism that points to mediawiki namespace pages that define these link targets (like the mediawiki namespace pages defined by MediaWiki:Sidebar). A possible syntax could be done with {{subst:Mediawiki:PAGENAME}} templates (however this syntax has some problems as this would need to expand to a given sub page and would need to check if that sub page exists and fall back to default if not). Another possible syntax could be the use of named variables such as $MediaWiki:PAGENAME in interface strings.

Arnomane