If the text color of a region is changed, the color if the corresponding description (if any) is not changed in the current session.
After saving and re-opening of the file, the description adopts the new text color of the region. Switching off and on the display of the description does not update the color.
I would not mind the description to not change color at all. That would be more consistent than the current behaviour.

Martin Kraska
Pre-configured portable distribution of SMath Studio: https://en.smath.info/wiki/SMath%20with%20Plugins.ashx