According to T168061#5386265, we should see similar (actually better) search behavior by switching to Phabricator's built in search engine. It's not the same as what we used previously, the built in search has been overhauled completely since the last time we used it.
The built-in search seems to have good quality search results, however, it only shows titles in the search results. With elasticsearch we have contextual highlights to show matching words from the page body.
After looking at it in depth with @brennen, it looks feasible to implement context highlighting for ferret search results, however, it's not exactly straightforward. Some notes from our investigation: https://etherpad.wikimedia.org/p/phabricator-search