I do these attribute rules for a federated service
Coordinates
//Latitude
var y = Centroid($feature).y
var originShift = 2.0 * PI * 6378137.0 / 2.0;
var lat = (y / originShift) * 180.0;
lat = 180.0 / PI * (2.0 * Atan( Exp( lat * PI / 180.0)) - PI / 2.0);
return lat
//Longitude
var x = Centroid($feature).x
var originShift = 2.0 * PI * 6378137.0 / 2.0;
var lon = (x / originShift) * 180.0;
return lon