This makes me sad... you did a great job matching the colour and it was looking great until it got slightly yellowed by the clear. I bet the varathane will resolve most of the problems. Matching headstock would look great on stage.I don’t want to go through that again. The sanded headstock is getting clear coated as is.
If you don't like the varathane you could try an acrylic spray lacquer, they are usually pretty clear. If you do decide to give it another shot, I'd recommend finding a scrap of maple and doing a test piece including spraying and wetsanding just to clarify the process.
There's still almost two full months until the end of the SBO.

)