Partial result

It’s not something you’re doing wrong. It is a limitation of the fulltext index of mySQL uses that the plugin uses.

It’s also something that I’ve been working on to retrieve better results. To be frank, I haven’t been successful yet.

In theory words like folder* would work in BOOLEAN mode. You might need a snippet of code to make the results a bit better for your site depending on what search terms are typically used but you might need to look at what the search result is generated and tap in with some filters.