Thank you for the proper details, I managed to figure out where the page builder stores all that information.
It turns out, everything is stored within the 'zn_page_builder_els' custom field. So I went to the index table options, and selected that custom field for indexing, and then re-created the index table. It managed to index over 100 000 words now: https://i.imgur.com/mYN2Unl.png
I have tried a few strings from the page contents, and so far it appears to be working for most cases: https://i.imgur.com/3YF6pxO.png
It may not be perfect, but it should do the trick 🙂 I have also de-selected some of the post types on the General Options -> Sources panel for better performance, since I believe you only want the pages as results.
I hope this helps!Best,
If you like my products, don't forget to rate them on codecanyon :)