In localization file I tried $specialPageAliases option.
If alias contains space, then wiki creates link replacing space with underscore,
but if I click link, then I get message that special page not exists. But if I
enter alias with _ in $specialPageAliases, then it works ok.
Also special pages with extra options like Special:Watchlist/edit redirects to
Special:WatchlistTranslated losing options.
Special:Search does not redirect to Special:SearchTranslated and says that
special page not exists.