kind: not working with this plugin

[Zman67]

After indexing epubs (I literally have tens of thousands) the searches work in Spotlight.
I'm a datascientist so if I type the word "heteroscedasticity", epubs appear. But just like with PDF's I'd like te be able to select te "kind" of document. So if I type: "kind:pdf heteroscedasticity" Spotlight only shows the PDF's with that word.

However when I type: "kind:epub heteroscedasticity" it doesn't find any epubs with that word.

[chrisridd]

It looks like we index pubs with a kind like this:

kMDItemKind                            = "Electronic Publication (EPUB)"

Does using that magic string help at all?

Hint:

1. open Terminal.app
2. enter mdls (with that trailing space)
3. drag an epub file into that window
4. hit return.

You should see all the indexed fields for that file.