Unfortunately, that is a result of the how the Kobo search engine and that Kobo works in a global environment. And how the plugin works with that.
When you run a search, Kobo works out were you probably are, and returns the results for your country. And the plugin uses those results. If Kobo does not sell a book in your country, a search will not find it. I get similar results to you as the book is not sold in Australia.
If you have the id for the book in the Kobo store, you can view it regardless of where you are. And if the identifier is set in calibre, then the plugin should get the details. The link for the book is
https://www.kobo.com/au/en/ebook/the-babysitter-37. Copy that to the clipboard and click button to the left of the identifiers field in the metadata editor, and it should add the correct identifier.
There is a way I can work around this in the plugin, but, it has never seemed worth it. This is only the second or third time the issue has been raised since I created the plugin years ago.