[11:56:02] <grin[m]>	 Okay, folks, this is not strictly wikidata, or wikidata only, but maybe can figure out the solution.... (full message at https://libera.ems.host/_matrix/media/r0/download/libera.chat/379e5492475015955861e6eef1703ac807533d4b)
[14:33:23] <markh>	 grin[m]: creator = some value just means that the creator doesn't have a Wikidata item, which is normal when it was not created by a notable author.
[14:33:37] <markh>	 I don't think that WikibaseCirrusSearch has a way to find statements with a value of some value (aka unknown value).
[14:33:59] <markh>	 For creator I think there is usually a commons category for that, e.g. https://commons.wikimedia.org/wiki/Category:Pictures_by_Madboy74
[14:34:27] <markh>	 Or you can get all uploads by a user, e.g. https://commons.wikimedia.org/wiki/Special:ListFiles/Madboy74
[14:35:01] <markh>	 If you want to do some more complex query using the structured data then you can use the (beta) Commons Query Service.
[14:35:08] <markh>	 Currently it requires OAuth authentication first.
[14:35:16] <markh>	 See https://commons.wikimedia.org/wiki/Commons:SPARQL_query_service
[14:35:29] <markh>	 You can find some example queries at https://commons.wikimedia.org/wiki/Commons:SPARQL_query_service/queries/examples
[14:38:18] <markh>	 grin[m]: To look for a specific author name string on Commons you can use a query like this: https://w.wiki/5JSN