[fjfaase]

How to correct errors? I found some museum with the name that matches a city (but not exactly) to be placed in that city while it is in a city at the other side of the country. I guess some AI has been used.

Also some markers refer to areas and they are just placed at the center of that area. The marker for a country just placed in some random field.

[yorwba]

I guess it's based on Wikidata's "coordinate location" property. You can find the Wikidata item corresponding to a Wikipedia article using the "Tools" dropdown in the desktop view. (Or just search on Wikidata directly.)

[mukul-mehta]

The data comes from Wikidata's P625 coordinate location property. It has to be corrected on Wikidata itself. Could you share some examples for where you think the data is incorrect?

[fjfaase]

I corrected the location for https://en.wikipedia.org/wiki/Museum_Ensched%C3%A9 to the address mentioned in the article. It was placed somewhere in the city of Enschede.