I am unable to get the value of latitude and longitude for view map event when spatial reference is using 3414. May I know what is the cause? It has value when spatial reference is in wkid 3857.
You can use the projection engine to convert the geometries.
https://developers.arcgis.com/javascript/latest/api-reference/esri-geometry-projection.html#project
https://developers.arcgis.com/javascript/latest/sample-code/client-projection/
The only time you will automatically get the lat/long is when the spatial reference is web mercator.