Hi B-chan,
there's no possibility to understand exactly what you are hearing in your space but I'll put some ideas forward which I feel fundamental to this.
If you have a desire or need to change or regulate very specific physical things about a piano, like a good piano tech would be able to do in person with a real piano, like altering unison width and balance, these and other voicing settings which go beyond this, many you will find included in Standard.
But, certainly, if you feel you'd appreciate control over this type of treble range alone, whilst standard does give more tools than Stage allowing editing many aspect of the whole piano, Pro will allow you ways to only operate for instance, on a select range of notes or per-note which allows you to keep everything about the bass you love unchanged, while altering just a few octaves, or notes.
So in general, Standard tools will mostly alter overall tone in all ranges - so possibly Pro allows therefore less concerns for "balancing edits", faster, deeper changes etc.
From what you describe though, it may be possible to alter "Equalizer" a little. You haven't mentioned if you've tried certain things like it - but in case you're not sure how these work well for us..
Try clicking the Equalizer button as a first step, and try lowering a little treble. (intuitively, you can use dots and drag them up or down, right-click them to adjust precisely by typing in numbers if it's important to be exact).
So many ways to apply EQ, it can seem tricky at first - but, you don't need Standard for this and other "Effects" which also include a extra EQ tools.
The extra EQ tools inside Effects is called EQ3, which are parametric type EQ.
With these you can shape greatly or in small notches. You can click and drag the middle dot up (it will increase a small frequency band, you will hear that 'character' boosted too much).
Then just drag the dot left and right, until you hear the tonal range you don't want.
When you've discerned that frequency range by ear, made a few short experiments to be sure it's 'the one to remove' - then lower that dot to below the line, so you are effectively disallowing it in the piano.
You might find, lowering it by only under 2dB might be well enough - and by lowing or raising things in larger numbers, you may have less genuine success in helping along your presets.
Last thing, I would take note of that frequency - because, you might be better sometimes to find it with EQ3 tool, but then close it, use the main EQ to create a small 3 dot cut of 1 or 2 dB at that same frequency instead - just a few thoughts.
I'm not sure what preset you're using but, you can select the below text, copy, then paste that by right-clicking in the Equalizer pane..
Equalizer = [116, 183, 300, 1530, 4000; +1.9, 0, -2.0, +1.0, 0]
See if that helps, it's the "cinematic" preset's EQ curve with a 1dB cut in an upper-mid frequency..
if that works to an extent, it may give you clues or serve as a nice starting point for you.
Hope that helps with this.
Pianoteq Studio Bundle (Pro plus all instruments) - Kawai MP11 digital piano - Yamaha HS8 monitors