Have worked with this issue in Standard, perhaps it requires Pro.  Have noticed a tendency among all the pianos for strong, bright bass, midrange a bit softer, and an almost overly brilliant top two octaves.  I like a piano that is bright overall, but when I adjust dynamics to brighten the midrange, the top becomes far too brilliant by contrast. But this discrepancy is noticeable no matter what the adjustments.

Have played with velocity and equalizer curves (best for me is flat response--what you get by hitting the Reset button), reverb, hammer hardness, etc.  Is this a "thing" in Pianoteq, and will I have to adjust note-by-note in the treble with Pro to fix it?

Pianoteq is amazing, btw.