I believe that yellow is the color of Eyemancy and that Wanda used either Thinkamancy or Foolamancy (if Thinkamancy is read-only) to make Mung suggestible. So, to me, the color of the sparklies doesn't contradict the possibility that Wanda cast a mind-reading spell from Thinkamancy on Jillian. I'm leaning toward thinking that it was a suggestion spell for other reasons.