Original Broadcaster, Telecaster, Nocaster were every shade under the sun. Originally they would all have been very pale. The pigments in nitro-
cellulose paint are organic and literally continue to decay.
There is a picture somewhere of the Rev Billy Gibbons and his black and whiteguard collection. They are every shade of yellow from chalky banana milk, to greenish, brownish, orange, stark yellow.
Nitro is highly reactive to tobacco smoke, sweat, UV, beer. It really depends how the guitar is handled.
Plus - ash varies from white-yellowish-brown. And the guys painting, would fog more or less paint on to cover joins and the paint was different brands, handmixed with a slop of this, a slop of that tins and applied in every weather. Shoot in cold/damp you get a whiter bloom opacity. Add more or less clear on top. It was a cottage industry, there was no consistency.
So a 'pumpkincaster' is Fender's attempt to replicate an old barroom queen after 40-50 years. And who is to say it's wrong? Later 50's were whiter. But the earlier 50's ones were yellower. The guitars below were not even blonde - they started out as Olympic White! And they are original 50's-60's guitars, unrefined.
To lighten, you could try stripping the guitar down to the body and bleaching but it's unlikely to have permanent effect and may just damage the surface and make it more matte. You could get a milky wash shot over the yellow, but the results may look just as fake. You will certainly devalue the instrument. I'd learn to like it, or get a CS guitar which may or may not be more accurate. Personally, a whiter guitar would just be a custard- or blancmange-caster. I like yours.
No-one can definitively say it's 'wrong' unless you're friends with Doc Brown and his flux capacitor is working..... And even then, all the guits in 1955 probably looked like a MIM 50's classic.