Nope, not a typo, promised.
The display message was :
"Set <b>{0}</b> as support for the board" where {0} is an object from an object parameter. (The picked object that had the check failure was a Sprite).
It seems like the output of the object parameter already is formated like: <b>Name of the object</b>. Then using "<b>{0}</b>" gives the check failure once you setted up the action in C2 during edit time.