I have noticed that API geosearch doesn't work with same pages.
For example https://en.wikipedia.org/wiki/Florence_Baptistery has coordinates: 43.773224, 11.254602.
geo_tags table has the row:
SELECT gt_lat, gt_lon FROM geo_tags WHERE gt_page_id=691612;
43.77322388, 11.25460243
but the query centered on these coordinates:
doesn't return "Florence Baptistery", neither using gslimit=1000.