I agree with you that someone must have experienced reactivity and/or hyperacusis before getting a cochlear implant. I read about a woman who considered getting a cochlear implant for a while due to single-sided deafness. I know she struggled with severe tinnitus, but I'm fairly certain she also mentioned having hyperacusis. She eventually decided to get the cochlear implant, and I believe she said it significantly reduced both her tinnitus and hyperacusis.
I suppose it depends on the location of the hyper-excitatory nerves, synapses, and other factors that contribute to someone's sound sensitivity or reactivity. Suppose those misfiring/excitatory factors are in the inner ear. Would they need to be "eliminated," as happens with a cochlear implant, before the device begins sending electrical signals through the electrodes in the cochlea?
I apologize if my thoughts seem unclear or don't align with the studies. I've done much less reading and research for a while now for the sake of my mental health. Ultimately, we know that many people who suffer from tinnitus severe enough to affect their quality of life—those who would be candidates for these types of implants—are also troubled by reactivity and/or hyperacusis. As I mentioned before, it's the severe sound-reactive component that prevents me from fully living the life I once did.