I would use a sun without a target (as suns position is irrelevant in corona), and just worry about the 3 axis rotation.
Try the below:
sun =Coronasun()
sun.name = "scriptedSun2"
sun.position = [0,0,300]
sun.targeted =false
fn easyRotation obj x y z =
(
try(obj.rotation.x_rotation = 90-x)catch() -- Invert the height as 90 should be up and 0 should be down for the sun
try(obj.rotation.y_rotation = y)catch()
try(obj.rotation.z_rotation = z)catch()
)
easyRotation Sun 0 0 0