The AMA "Alpha" kit comes with formed polyfoam flying surfaces that are covered with a thin plastic film. Does that place it outside the specifications for the event?

No, Para 3, construction parameters does not define the structure or construction methods, it only limits pre-glued joints on kits and no boron fibers. Thus a solid sheet foam or balsa wing is acceptable assuming all other parameters are met. This does not give carte blanche approval to that particular kit, only to the concept of solid panel wings.