probably?
maybe?
For clear coat it’d all come down to transmission of UV frequencies. If the coat doesn’t block it, I don’t think it’d affect the fluorescence at all. UV comes in, visible spectra comes out. We know clearcoat lets visible spectra pass through (hence appearing clear), so as long as it lets UV get to the wood I bet it’d glow just fine.
With stains, they filter visible light spectra, so I’d expect the glow to be reduced to some degree… though I dunno, the easiest way to tell would be to try it 
That being said… yellowheart is so ridiculously gorgeous when you sand it to a high polish, it gleams like metal with chatoyancy and character. Check it:
I wouldn’t put stain on it, it’s amazing.