This might be complicated to solve and is wiki-specific, so I'm marking it as an enhancement for now.
The English Wikipedia uses a /lot/ of locator maps, which are built by templates that overlay data to build the image (ref: https://en.wikipedia.org/wiki/Template:Location_map%2B).
Media Viewer can't currently handle these image overlays properly, displaying only the "top" of the image (example: https://en.wikipedia.org/wiki/Template_talk:Geobox/test1).
If this can be fixed, that would be wonderful.