You did well though.I know very little about budgie mutations, but I do have a pied, so I know what a pied spot looks like. It is very broken up and light so I wouldn't call it a pied spot, but what do I know about mutations lol. Really, I wouldn't take my advice it is just a guess.
Thanks RIPbudgies! Nice explanation as usual.Not a pied spot. The pic of the wing showing the wing area is what is known as a 'wing miror'. All australian parrots have an underwing stripe which is not visible on the upper side of the wing but is seen quite well on the underside and does not extend to the out primary wing feather. In the Opaline mutation this stripe is altered to appear on the upper side of the wing feather and is extended to the outer most edges of the flight feathers.
Pied spots can vary in size but they are always in the back of the head region and formed from an area known as the 'neural crest'.
Just slightly off topic but your 4th pic is a great example of taking photos of the same bird in different lights can alter the visual outcome of the bird. In one photo it looks Goldenface yet in another YF M1(sf) and in another YFM2 (df). I would really love a copy of that photo if at all possible and will credit you whenever it is used.