Deeply dark ebony will be the same color through it's full depth - it's not a matter of just removing the surface color to change it.. It's prized for it's dark character and density. I don't think ebony would fade much under any circumstance and I'd personally avoid trying to force it. Chemicals used might excessively dry the wood, which could create other issues like cracking or warping. Ebony is known to be a wood that seldom requires any protective sealing finish, because it's own natural oils will protect it over time. Those are the oils that might be stripped from it, if using harsh chemicals to alter it.
Some lighter woods do change color as they age, either fading, losing color (going gray) or darkening. But I don't think ebony is known for that, being a wood that's famous for holding it's color and dark character for decades or much longer, even a century or more. It's practically ageless in that regard.
I think if you're really wanting to change the look of the covers, it may be worth having somebody replace them with something more to your liking.