I have been testing and found two details:
1 - The color for the text of lines without use "gui_color_empty", will not update when changing the theme, in some cases I have to assign a vehicle and sell it to see the color change.
2 - The color for the text of lines without red numbers "black text" does not accept the parameter "gui_color_text".
Yes, the lines recalculate their status only upon change. This is intended. Latest after a month there should be a change. Changing the GUI colors is not that frequent.