[out:xml][timeout:3600]; ( way(173059107)['wikidata'='Q59508740']['wikipedia'='de:Geomagnetisches Observatorium']; ); (._;>;); out meta qt;//['wikipedia wikidata mismatch']
[out:xml][timeout:3600]; ( node(1265582090)['information'='board']['wikidata'='Q878838']; ); (._;>;); out meta qt;//['information board with wikidata tag, not subject:wikidata']
[out:xml][timeout:3600]; ( relation(1528130)['wikidata'='Q514612']['wikipedia'='de:Köhlen']; ); (._;>;); out meta qt;//['wikipedia wikidata mismatch - wikipedia points to disambiguation page and wikidata does not']
JOSM Wikipedia plugin
Note to self: online version hosted at https://matkoniecz.github.io/OSM-wikipedia-tag-validator-reports, files are stored at https://github.com/matkoniecz/OSM-wikipedia-tag-validator-reports.