I have been polishing my guitars every string change for the last 5 years. I always polish the fingerboards too. I spray the polish on and take a cloth and rub it and shine my frets and the wood. I have rosewood and ebony fingerboard too. It's never done any damage and it looks very nice. I know I should use actual fretboard conditioner or lemon oil but will polish hurt the actual fingerboard ?? I don't see why it would but I want to make sure.
It will not damage the fretboard, but the wax in the furniture polish might build up and get rather gummy after a while. Better to use a good fretboard cleaner on the bare rosewood and ebony fretboards.
"Maybe this world is another planet's hell?" - Aldous Huxley
I use guitar polish. I don't think there is wax in it? I just used lemon oil on my 25 year old Gibson Sg's rosewood fretboard. It really shined it and made the wood feel really nice.
Some guitar polishes have a wax base in them - that is what makes the surface of the guitar shine. But if it is just a lemon oil cleaner, then it should be OK. Do not overdo it on a rosewood fretboard. Rosewood is more porous than ebony or maple, and too much oil could conceivably cause the wood to warp. An occasional cleaning is just fine, though.
"Maybe this world is another planet's hell?" - Aldous Huxley