Edit image metadata in remote repositories from the downstream wiki (not just getting but also setting) (also, would be useful if this happened after Commons was Wikidata-fied so we could edit all kinds of cool stuff like descriptions, authours, locations, categories, in granular fashion)
Challenges:
No real established way to do edits from one wiki on another wiki yet; CORS and SULF magic pixie dust can solve this? [ForeignApi in MobileFrontend has a generic way of doing this)
Does the silo accept the edit ? [YES] Does the editor find out? (Cross-wiki notifications) [NO]
(these have similar, but different problems - need to follow the downstream/upstream connection the opposite direction)) Suggest (ext) -> Review (int) -> Publish (ext)