I will put in a guess of who "The Jaguar" is. I am only vaguely suspecting that I am right, but it works.
From "Soul Mates" we learn that not only does Clark have multiple incarnations, but they all look essentially alike. Well, when baby Clark died, his soul moved on to its next life.
The Jaguar is this universes' Clark's next incarnation.
My other thought is that the mask has magical powers that mess with Superman's x-ray vision and obscure the truth of the wearer.
