Hi,
Yes, customisation does need to be done to fully integrate the plugin. The plugin is very powerful and as such requires some reading to be sure the plugins settings are correct.
The main modification is search result count, it need’s needs to be changed. Ie, 0 Results will always show, even if there are results returned, full article: https://www.relevanssi.com/knowledge-base/found-posts/
Please read up on their KB: http://www.relevanssi.com/category/knowledge-base/.
Thanks,
David.