I have tried the new text search plugin, I know this is still under development, but perhaps this will help.
- First comment is that the plugin has to be inserted into the page, whereas the search plugin in 3.x was coded into the template so that it appeared in all pages.
- I am working with a 2 language site PL/EN. When doing a text search in on the PL side the search plugin finds the word on the EN side and gives a link to the page on the EN side. When I click on the link on the PL side I get a 404 message.
If I repeat the search (same word) on the EN side, the the search plugin finds the word, gives the link on the EN side (same link as given in the PL side) and when I click on this link I get the correct page.
So it appears that the plugin searches the whole site but cannot complete links when the text is on the other language side on the site.