When the user clicks on an edit button of an included page, he is redirected back to the including page after editing the page. This means that the indexer won't be triggered for the edited page, see also dokufreaks/plugin-tag#150. A possible fix could be to try updating the search index before the redirect (if it is fast enough and not disabled which might be hard to detect?) or to embed the indexer web bug of the included page after the redirect (which might be difficult, too, and might also cause side effects if the indexer web bug is not in the template normally).