Imo the previous owner liked gold everywhere, look the tweeter cover is also gold painted

... did it listened to RAP ?
However some manufacterer made gold or stabilised brass deposit (?) because the price of gold on aluminium domes. I dunno if some made it with electrolytic method which is thickier?
Theorically the softer uper surface ads damping - Young Modul of some soft metal like tin, gold or lead would help -
a typical 1" tweeter dome is around 0.3 g and such micro grams deposit of nano meter thickness has certainly no weight effect that changes the T/S parameters that can be heard ! So less stifness and more damping (more heavy and more elastic metal)

??? Strange they are looking for the opposit with diamond vapor deposit stifier and lighter !
My bet is it's pure marketing...gold looks richer so is the price !
you want to know for sure : try thin sheet of pure gold they use in art refurbishing or 100% domes of other materials... If I was Bill Gates just because I can I will try plain gold dome, tin dome, brass dome, maybe titaniu or beyrillium (uh, already made, too bad

)... and stronger magnet for weight compensation ! But some clever guys that know more abut physic laws than computer solved it a different way : shapes of the domes, horns, aramid or carbon tissus, etc !
That's for tweeter domes, now if talking about paper cons, they drink liquids, so the dampin effect should be heard because the weight becomes significant (maybe as sticky heavy material on some tweeter domes like Dynaudio which may be 0.1 g heavier ?)... gold painting would hane no particular advantage over green, blue, your prefered color after drying but the added weight that change T/S parameters and cones break ups - complex phase behavior due to complex cones break ups that certainly very few manufacterers have modelised with laser measurement and or at least understood it really when sound is involved ! But voila, say it and you will have more marketing sucess !
I can't believe I lost 10 minutes of my life to write this... our hobby is fantastic

... all those questions helps the brain to stay young ... doubts alays doubts... I'm not the last either

. But all is about perspective when efficienty of the question is involved ! sometimes you hear something just because your eyes saw a measured difference on the graph...can you hear it is another question...