Is it Dollyhair "Butterfly"?
This one is named for Dancing Butterflies hair (I think) I discovered it as it also goes to the green Glow n Show who has yellow stripes, but they are not AJ Yellow=Golden Delicious yellow. I think this Butterfly Yellow is a tad lighter than the Golden Delicious. It may be what you need, if others agree.
Mango Tango is darker.
I don't have Crumpet either, which is a problem with this one. It def. has more orange in it. I would say this is not it for Pretty Belle. (At least, not mine for certain)
If you can hold yours up to the green Glowshow, or Dancing Butterflies & see if it's close/similar/looks like it could have been before it faded, it could be a key.
Sorry to not have 100% confirmation here but if others can say too, it's a start.