Thread:Help talk:CirrusSearch/Subcategory searches via incategory/reply

No, it doesn't. As far as I know, the scope of search is limited to information that's part of the page itself, which only includes categories that it's a direct member of. You could try catscan... although that doesn't provide text search. Theoretically you could approach this with a [Help:CirrusSearch#insource:|regular expression search], but that function doesn't seem to be working reliably at the moment. Also, note that adding multiple "incategory:" terms will imply AND logic, and you will only get results that are in all of the listed categories...