Manual:$wgExtraInterlanguageLinkPrefixes/ja

詳細
By default, only treats interwiki links as interlanguage links (i.e. moved to the "Languages" section of the sidebar) if the interwiki prefix matches one of the ISO language codes known to MediaWiki. From time to time, you may need to set up extra prefixes that are to be treated as interlanguage links (e.g. "mul" for a multilingual site).

に true を設定していない場合、この設定は無視されます.