As mentioned on https://www.wikidata.org/wiki/Wikidata:Project_chat#Error_with_extraterrestrial_coordinate_locations_.28P625.29, the GeoHack URLs generated by https://www.wikidata.org/wiki/MediaWiki:Gadget-AuthorityControl.js don't take the current user interface language into account and instead always link to GeoHack in English.
e.g. https://www.wikidata.org/wiki/Q153972?setlang=de currently links to https://tools.wmflabs.org/geohack/geohack.php?language=en¶ms=49.701388888889_N_6.5697222222222_E_globe:earth when it could link to https://tools.wmflabs.org/geohack/geohack.php?language=de¶ms=49.701388888889_N_6.5697222222222_E_globe:earth