This particular study looks like it's dealing with a pretty narrow condition and solution (protein missing - add gene for protein). I don't think this particular research can be extended the way you hope.

Yes, I would really like to see research targeting Connexin 26, since it's the most common cause of hearing loss, but it seems it's much more difficult to "cure."

I agree. The causes of deafness I mentioned are diverse and fall outside the specific focus of this current study. Ideally, future research will address deafness caused by these and other other factors.