Links would have made this clearer… 
For anyone else wondering, if you filter on this Umbreon there is a regular Lost Thunder version; a Blister Exclusive promo; and an Alternate Promo:
The non-Holo and Reverse Holo are in the set; the Cosmos Holofoil comes from the Unified Minds Blister below; and the Alternate Art promo is most likely just an error on TCGPlayer’s part as you suspected.
I also don’t see an additional fourth Lost Thunder artwork Umbreon in @eeveeteam 's collection thread, so it most likely doesn’t exist.
Greetz,
Quuador