Thanks. Great with a specific explanation!
I have been using WP Engine for a few years now and I have been impressed by your customer support and am generally happy with your service. I think it is excellent for instance that you for example analyse plugin performance and advice people not to use some plugins.
But I am frustrated by the "related posts" functionality.
Initially I used Yarpp, until it became disallowed.
I did use nRelate, that you recommend, but it has become incompatible with WPML with the recent updates (of WPML). And WPML unfortunately takes priority. (the site does not work without it)
I am testing Reverb that you also recommend. But it seems that it can not handle multilingual contents.
I have seen it mentioned that Yarpp can handle multilingual contents and can work with WPML, which is why it would be very interesting for me. However, it is on the disallowed list so I can't.
So now I'm without any functioning related-posts plugin, which is bad for keeping visitors on the site.