I deliberately replaced the local link with a full URL, because there might not be a local help page in the user's set language. One solution would be to make the link depend on content language of the wiki (wfMsgForContent ?) not user language. That way however, users will be directed to a page that might not be in their language and the link would not default to English, if the message is not defined/translated in user set language. I hope this makes sense.