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What a colorful Community post! :-)

Vitaliy, another way to have text in contrast is to use your trick posted in Stackexchange

text = First[First[ImportString[ExportString[Style["gray", Italic, FontSize -> 24, 
FontFamily -> "Times"], "PDF"], "PDF", "TextMode" -> "Outlines"]]];

and setting the fonts to be always black with white borders:

Graphics[{EdgeForm[Directive[White, Thick]], Black, text},
Background -> Gray, PlotRange -> {{-5, 25}, {-0, 20}}]

Btw, your awesome function to find color relationships can be used as a "Color Blind Assistant". Here is the modified function that does this given a color:

cassist[c_] := Part[Nearest[data, {c, ""}, DistanceFunction -> neco],1,-1]

for example:

cassist[Darker@Red]

"darkish red"

Which it really tells how that particular color looks like.