[out:xml][timeout:3600]; ( relation(4766541)['wikipedia'='de:Erms (Fluss)']; ); (._;>;); out meta qt;//['wikipedia tag links to 404']
[out:xml][timeout:3600]; ( node(4092312659)['wikidata'='Q694197']; ); (._;>;); out meta qt;//['should use a secondary wikipedia tag - linking from wikipedia and wikidata tag to a human']
[out:xml][timeout:3600]; ( node(1531223570)['wikidata'='Q76631848']['wikipedia'='de:Spendhaus']; way(295791660)['wikidata'='Q98818024']['wikipedia'='de:Römerstein (Berg)']; way(334341345)['wikidata'='Q123860085']['wikipedia'='de:Liste der Kulturdenkmale in Metzingen']; way(334341436)['wikidata'='Q123145549']['wikipedia'='de:Liste der Kulturdenkmale in Metzingen']; ); (._;>;); out meta qt;//['wikipedia wikidata mismatch']
[out:xml][timeout:3600]; ( relation(16750608)['wikipedia'='DE:Liste der Kulturdenkmale in Metzingen']; relation(16750609)['wikipedia'='DE:Liste der Kulturdenkmale in Metzingen']; relation(16750610)['wikipedia'='DE:Bindhof']; way(204053709)['wikipedia'='DE:Liste der Kulturdenkmale in Metzingen']; way(284088000)['wikipedia'='DE:Liste der Kulturdenkmale in Metzingen']; way(284088004)['wikipedia'='DE:Liste der Kulturdenkmale in Metzingen']; way(327130429)['wikipedia'='DE:Liste der Kulturdenkmale in Metzingen']; way(335276796)['wikipedia'='DE:Liste der Kulturdenkmale in Metzingen']; way(335903480)['wikipedia'='DE:Liste der Kulturdenkmale in Metzingen']; way(335903498)['wikipedia'='DE:Liste der Kulturdenkmale in Metzingen']; way(335903744)['wikipedia'='DE:Liste der Kulturdenkmale in Metzingen']; ); (._;>;); out meta qt;//['malformed wikipedia tag']
[out:xml][timeout:3600]; ( way(229823238)['name:etymology:wikipedia'='DE:Hermann Löns']; way(30568057)['name:etymology:wikipedia'='DE:Hermann Löns']; way(35957318)['name:etymology:wikipedia'='DE:Hermann Löns']; way(6079489)['name:etymology:wikipedia'='DE:Hermann Löns']; ); (._;>;); out meta qt;//['malformed secondary wikipedia tag - for name:etymology prefixed tags']
[out:xml][timeout:3600]; ( node(1835256298)['operator:wikidata'='Q2400658']['operator:wikipedia'='de:TeilAuto']; node(7918978265)['operator:wikidata'='Q41171672']['operator:wikipedia'='de:Aldi Süd']; ); (._;>;); out meta qt;//['wikipedia wikidata mismatch - for operator prefixed tags']
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.