cyanidin 3-O-(6-O-glucosyl-2-O-xylosylgalactoside) betaine + 1-O-[(E)-4-coumaroyl]-beta-D-glucose = cyanidin 3-O-[6-O-(6-O-4-hydroxycinnamoyl-beta-D-glucosyl)-2-O-beta-D-xylosyl-beta-D-galactoside] + beta-D-glucose + H(+) — reaction