I don't think the velocity curve has any bearing on CC7, but I might be wrong.
The thing that came to mind was a vague memory of people talking about having trouble with the Channel Volumes when they were using the Live Control knobs to try to balance the parts (voices) on some of the PSR-S models, but I don't recall the details of that issue.
The only other thing that comes to mind is actually more specific to the PSE-E models, which don't have a Mixer for setting the Channel Volumes of the individual parts of a style. On those models the volume of each style part is set within the style and can't be changed, but the Style Volume function can be used to adjust them en masse, such as turning all of them up or down relative to their default settings. I believe that on those models the Style Volume acts like a percentage multiplier, with 100 meaning 100%, 50 meaning 50%, and so on. If that's correct, the maximum Channel Volume for any given style part will be 127% times its default setting, such as 1.27 * 80 = 101.6, which I assume would be truncated to 101. But I don't know if the Genos has any functions which are at all similar to that.