I confirm that pressure will modulate uninitiated while gliding, but I don't see as drastic value changes as you. Here, if I use the lightest touch I can muster the pressure value will cycle between about 5 and 10, maybe 15. Still very noticable, depending on the patch.
Videographics
I've noticed that when doing slow "smooth" glides using very even light pressure, the Press values will very noticeably cycle between 0 and the middle range (64) as I pass each "note." I expect this is an artifact resulting from the inherent design of the Seaboard Rise's sensor array, but I thought I'd ask about it.
(To see an example of this, pull up the Acid Funk Overdrive Bass patch on Equator and watch the modulation panel for Press as you do slow smooth glides using even light pressure.)