Recently, we have been thinking about how to improve the Wikibase interface, to get around its limitations - such as the lack of on-wiki queries.
One other tool that seems like it would be worth including in the discussion there is LinkedWiki: https://mediawiki.org/wiki/Extension:LinkedWiki It can also create a table or a map from a SPARQL query, and related Lua functionally.
Regarding your proposal at the end, it reminds me of Cradle, which can use EntitySchemas to define types for creation; e.g. https://furry.wikibase.cloud/tools/cradle/?#/shex/E2 Perhaps it would be worth expanding that project to editing instead? The source is MIT-licensed: https://github.com/magnusmanske/cradle
https://furry.wikibase.cloud/tools/cradle/?#/shex/E2 I agree it would be useful to have these tools more integrated into the UI itself, rather than as a constellation of clunky-looking add-ons.
-- Laurence 'GreenReaper' Parry - WikiFur.com