Does water based polyurethane affect the color of paint?
You should give those last two coats of paint a good long while to see if it will get less tacky and "cure".

If it stays tacky I would not try to fix it by trying to plaster an incompatible product like polyurethane on top of the latex paint. This would be an especially big issue if the base paint was not fully cured and dried. In this case the best order of business is probably to buy a gallon or two of paint stripper and remove all the paint on that item and start over with the color that you want.

Note: Also be aware that when you had the paint store remix your paint color it is possible that the amount of colorant that was added exceeded the manufacturer recommended amount of colorant volume per gallon and that changed the characteristics of your paint.