crossing:island (https://overpass-turbo.eu/s/1Ggf) is more typically the tag used on the crossing way or node (though I see it is used a lot on areas as well in the taginfo stats...)

The areas are more commonly tagged as traffic_calming=island (https://overpass-turbo.eu/s/1Gga)

area:highway=traffic_island https://wiki.openstreetmap.org/wiki/Proposal:Street_area#traffic_island is also used a few spots... (https://overpass-turbo.eu/s/1Ggi)