T and H are 2 things not that different, they are interconnected. I do not understand how you can so positively say they are 2 totally separated conditions! When I get better at one, the other gets better too. In my bad days, they are both elevated together.
That all been said, I think there may be an improvement in BOTH T and H, especially in T loudness, which provides for better sound tolerance and less distortion. An improved hearing and less ear fullness is ALSO what comes form less tinnitus. They are all the same condition. This is my experience and I am quite positive about it.
Perhaps apart from getting rid of your H you also got lower T. It is difficult to know that your T is lower in volume if it doesn't change in pitch and behavior. But what I can certainly say is this: the more your T goes up, the more troubles it causes. There may be other ways to test your hearing, like listening to certain sounds or music and watch if distortion gets better. That is what I do.
I am hesitant to post any progress about Keppra just yet, since my condition is not stable: There seems to be generally better sound tolerance and clearer hearing, better masking from external sound than before, but I am not certain Keppra is responsible for this. And I also want to know if there is therapeutic quality to this drug or only a temporary effect. So, you will have to be a little more patient.
What I can say for this drug right now, is that it is relatively safe to use, meaning it is an old and tested drug and I do not seem to have any bothering sideffects by using it, compared to other similar ones. I haven't tried Trobalt, I don't know if it is worth it, since I aim to a cure, not temporary relief, let alone a possible temporary "placebo" relief. But I just can't say more for Trobalt since I did not try it, and I am hesitant to do so. Combining anticonvulsants is also something my doctor would hardly approve.