The map takes data from Commons page (in GeoJSON). Note that if Commons page contains localizable data, e.g. title or description are given in multiple languages, the data will be shown based on user's settings. For a test, login into this wiki, change your user interface to Russian, refresh this page, open the map, and click on the central park (long rectangle in the center of the map).
This method is different than using a Wikidata Query Service (service=geoshape). The geoshapes only allow access to the data available from OpenStreetMaps, but if one wants to document the trip that Don Quixote took through Spain, that data is not likely to be stored at OSM. Storing that data on Commons should help.
P.S. ?uselang=ru will not work - its a separate request.