As discussed with @Halfak: For https://www.wikidata.org/wiki/User:Multichill/Connecting_paintings_and_images I made https://commons.wikimedia.org/wiki/User:Multichill/Same_image_without_Wikidata . This page offers pairs of files that might be of the same painting. Matching is done based on de creator and the institution. Underlying database queries are available at http://tools.wmflabs.org/multichill/queries/commons/paintings_with_wikidata_ci.txt and http://tools.wmflabs.org/multichill/queries/commons/paintings_without_wikidata_ci.txt
Would it be possible to use this data to offer better suggestions?