I have a similar problem, the following added to a 2D sprite should print to the output any property that is changed on the sprite:
tool
extends Sprite
func _set(property : String, value):
print(property, " ", value)
It works if I change a property in the property inspector but not if I change something, scale for instance, by using the mouse in the visual editor.
I do not think there is a way round this, unless anyone has any suggestions?