In Appearance calling alternative color UI is done with Shift and not obvious Alt
For some we have to hold Shift while clicking a fill/stroke square in Appearance panel to call the alternative pseudo-panel.
Alt = Alternative. Sure, Macs have Option instead, but it also fits.
Also, the hint has the 'Shift' and 'Color' written in lower-case: 'Hold shift key to bring up alternate color UI'... and I have no idea why 'alternate', why no alternation happens? Who wrote this hint?
AdminEgor Chistyakov (Admin, Adobe Illustrator) shared this idea