The Trouble With Edward is indeed canon. Somewhere in the Federation, there’s Tribbles cereal, and someone who believes in it enough to make commercials for it.
“The Trouble With Edward” is canon, but Gene Roddenberry himself could descend from the heavens on the back of Kukulkan with Jeffery Combs riding shotgun to tell me that the Tribbles cereal commercial is canon, and my response would be, “Okay, but is it though?”