Sorry for the late reply, been busy with so many projects and one was building a 10 string Lap Steel Guitar for myself. It was a welcome break from doing violine fretted fingerboards. So to give some insight as to what you want, here's my thoughts and experiences on  matter. Take it for what it's worth.

The fingerboard is a a harsh environment, abrasive rosin dust is ground into the surface constantly and of course the normal heating and cooling from your fingers playing and then no heated object touching for awhile all tend to expand and contract the surface. This is probably why you don't see "painted" fingerboards, they are all stained or just ebony polished to a smooth finish.

On a guitar, like a violin the fingers actually touch the fretboard/fingerboard so there is an additional abrasion factor at work and of course I'm speaking of the string against the wood surface.

Now, armed with this knowledge you can now see why just simply adding gold leaf decoration to the fingerboard would look very nice initially and within I would suspect a few weeks will have lots of bare spots showing because you wore it off, sanded it off.

On a lap steel guitar I made this fretboard with abalone inlay and clear polyurethane coated it for protection and additional sealing protection from the environment because it's played with a steel bar and neither the strings nor your fingers touch it.

On my fretted fingerboards I do offer them with dots inlayed but the dots are very small and durable and clear coated so playing on top of them does no damage like it would on a gold leaf job.

Hope this helps your choice.