This is a good point. Carl LeBel did mention once or twice that patients opted to treat the "worse ear" with FX-322/Placebo. One can assume that the "worse ear" means the one with the greater hearing loss, which may or may not translate to worse tinnitus as well.
Carl LeBel also
mentioned in the Tinnitus Talk Podcast that some patients noted that they had improvements in their tinnitus. So, this may be an indication that even though it might be an improvement in one side, the measure may improve slightly. We simply do not know what happens to one's tinnitus if the "worse ear" is treated with a regenerative drug.
Speaking anecdotally, my "worse ear" is the one with the louder/noisier tinnitus. Both have it, but the right is worse. So, if I noticed over the course of a clinical trial that the treated "worse ear" tinnitus got quieter, perhaps to where the left and right were "about the same" it would be reflected in my TFI score.
It is also unknown the severity of the tinnitus experienced by the patients in the trial. A 13-point reduction in the TFI score is considered clinically meaningful. If they go in with a low TFI score (under 25 is considered mild), then the results of a single treated ear won't look great at all. Unless it goes to zero. If patients starting at a moderate (25-50) or severe (50+) score receive treatment in one ear, a considerable "quieting" of tinnitus in one ear may lead to a meaningful reduction in TFI.
If someone could reference possibly a correlation between TFI score and hearing loss, that might be a good way to understand what the expectations should be.
I do agree that it may be a bit of a mixed bag of results. With a P-value that may not be significant (<0.05).