The Russian phrases are not included with default VaultWiki, phrase translations are handled by vBulletin, and that options page is constructed by vBulletin. If a phrase is not being displayed, there is a problem with the language file you installed, or there is a problem with vBulletin.
Did you create the Russian language before or after installing VaultWiki? If it was after, have you run the VaultWiki upgrader since adding the language?
Did you try to install the VaultWiki language files manually using vBulletin's language importer? There are two language files for VaultWiki and it might not be possible to install both separately outside the upgrade process.