I'm still getting this fairly often (latest is for the search 'texture array ue "soft object"') - would it be possible to have a 'report this' button on the 'We haven't found anything.' box? For the most part if I'm working on something I'm not going to think to come here and post a screenshot, but for a search engine it's a pretty deep flaw.
Also wondering whether Kagi automatically notes down the number of times it can't find anything - I can't imagine there are many searches that actually should end up with no results, so presumably most of the time this occurs it's in error.