in page 5 of the rules says: The Empire, Dwarf, and High Elf races constitute the “Order” races. On the other hand, the Chaos, Orc, and Dark Elf races are nown as the “Destruction” races. Order cards and Destruction cards cannot be combined in the same deck.

i can't understand why the 4th in the polish tournament, with a dark elves deck, has a high elves card.

It doesn't. Deckbox isn't always up to date. At the time that deck was posted, the most recent pack(s) weren't in their database yet, so the person who posted the deck used a HE card as a placeholder. Usually, you can check the notes below the deck to see what placeholders stand for, or which cards are missing if no placeholder was used. The notes don't get copied along with the deck though, so you'd need to look at the original entry.