H Rich,
I have never used to reduce the colour from paint spills, how ever judging by the photos I see no reason as to why not an attempt should be made providing you let the custy know of your ntentions.
As you have asked for info on the use here goes, buy the powder from a beer/wine making shop ,mix a cpl of table spoons with VERY HOT water ,idealy put the so;ution in to a spray bottle herin lays the problem, quite often the water is too hot for the plastc tube ,but I have found if you simply put it in a bowl and dab on the mix with a terry towerl the results are the same, air dry with hair dryer and see the difference ,another application wll often improve it more. hope this helps.
Geoff