The search results page will work with the Unicode (UTF-8) encoding (version 3+ only), so non-Engish alphabeths will work fine. Even if your documents are encoded using a different character encoding, they will be indexed correctly.
Please note that it's highly recommended to also provide a character translation table ('search engine' menu -> foreign language support -> character translation). This is needed if you want the same results to be displayed when the users enter e.g. 'télévision' and 'television'.