Thread:Project:Support desk/"In other languages" on the "Search results" page/reply

Tell your local community admins to edit MediaWiki:search-summary and add Interlanguage links for other languages. Then, from the sidebar, you should have links to Special:Search in other languages. Note that those links will go to special:search on that language, but it won't carry the search terms you had input here.

You can also go to other languages easily prefixing your search with the language code. For example: "de:Something" to search "Something" in the german language.