I know there has been heavy debate in the past on what book is truly the first appearance of Phil Couslon, and the context of that appearance, but now it seems CGC has modified their labels to reflect their stance on it (see below.)
It seems Coulson is in the same boat as Harley Quinn, with both characters having "first" appearances in comics that are movie or TV show tie-ins, and then years later finally have a "first" appearance in their respective regular comic universes. I'm not sure w