No, an error because the swatch box doesn't match the shade that actually get's represented. MEDIUM is actually the shade of the LIGHT's swatch box but with white text. Either give us the option to change the shade manually, change the text manually, or fix it. Also, I can't use the program now.
VP15 and VP16 "light" interfaces are also the same for me. carl-johnson's 1st screenshot looks like my "medium" interface. Be sure to restart Vegas to see the effect of making a change.
I agree that the swatches in the preferences should be paler.