Where to go after Highlighter Yellow?

Palish pink over a yellowish base is normally the best way to get rose gold. I'm not really following your thoughts on maroon and light brown to make a rose gold. To me they're all far darker than a rose gold. Maybe we have different ideas of rose gold and maroon?

Can you post a photo of how yellow it is now? Can you post a photo of what you want?

If manic panic fades so much, maybe it just doesn't work with your hair. I have troubles with manic panic too, it fades for me even without washing. You could try another brand if you want longer lasting colour.

If you have yellow, I'd also try a light pink to get a rose golden colour. Try a very diluted colour first, otherwise you might get peach. You can always add more pink on a later dye.