All API modules should return information about the page containing an entity, e.g. the page and revision ID, in a consistent way. Some API modules currently report this inlined into the entity structure (e.g. wbgetentities), some don't return it at all (e.g. wbgetclaims) and some return it in a separate pageinfo structure (e.g. wbremoveclaims).
All modules should handle this consistently, by returning a separate pageinfo structure. IN case multiple entities are returned, care has to be taken to associate the pageinfo with the correct item.
Also keep in mind that UI modules need to be updated when the location of this information changes in the API output.