Can The Colour Code Variable Colours Be Changed?

Can the colour codes such as ^B which is blue and ^Y which is yellow, to name a few, be changed to another colour/adjusted or are they hardcoded? If so, then how may one go about doing so? I’ve already managed to make changes to item titles thanks to @DenisMashutikov but I was wondering if the same could be done for items on the floor tooltip.

They use the info from gameengine.dbr under the xItemColor variable which only accepts a string. If only it accepted RGB values like the item title/backgrounds do!