I set a my_card+*type+*content to type:Pointer (using the select menu when initially creating that plus card from the my_card+*type card), and I got the message "Application error. Oh, Man [sic]. You found a hitch in the Wagn". Below the error message, the +*content card appeared successfully transformed into a Pointer. You may ask "Why was I doing that in the first place?" Because I was trying to figure out how to make a plus card appear as a Pointer the first time it's edited, which I found another way to do.
So the card "my_card+*type+*content" would set the content for all the cards that have the type "my_card". If my_card is not a cardtype, there should be an error, because "my_card+*type" is basically a nonsense set -- the set of all cards of a type that doesn't exist. Obviously the error messaging needs improvements -- it should be more elegant and informative than a generic "hitch". I don't think we currently have anything catching impossible sets like that.
I think what you were going for may have been more like "my card+*right+*default". That tweaks both the Set and the Setting: