Currently, when a new category is created, even if it is linked to Wikidata and other language categories, there is no easy way to generate a list of articles that exist on a given wiki that should be populated with it. And even when someone has a list of such articles, they have to manually tag them. I'd like to see a tool that generates such lists, and allows populating categories with as much ease as Commons:Help:Gadget-Cat-a-lot.
See also a related discussion at w:Wikipedia:Village pump (technical)/Archive_141
--Piotrus (talk) 05:15, 10 November 2015 (UTC)
This card tracks a proposal from the 2015 Community Wishlist Survey: https://meta.wikimedia.org/wiki/2015_Community_Wishlist_Survey
This proposal received 23 support votes, and was ranked #38 out of 107 proposals. https://meta.wikimedia.org/wiki/2015_Community_Wishlist_Survey/Categories#Create_a_tool_to_auto-populate_categories_through_Wikidata.2Fother_wiki_comparison
Existing tools that solve (part) of this proposal: