Here I made a Colour Swatch using four colours from the above image.
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Using three colours from my swatch above, I made this gradient tile.
My main background tile is cut from the painting above, then I used the Effects/Image effect/Seamless Tile. For my text background, filled with the light purple and added swirls using the medium purple. Then I applied the Brush Strokes under the Art Media Tools and then lowered the Opacity to 54%..