You can use foreign language copies of legal-for-play cards printed for the TCG market, as long as you can show an official translation of the card, kept outside of your Deck and Deck box, when asked to do so by an opponent or tournament official
These parts include the set/expansion symbol, the frame, the color of the border, the rarity, the copyright symbol and date (if applicable), the corners, the foiling, and the art
These watermarks use a dot-based grid system to encode the printer's serial number and the exact date and time of when each card was printed
If youre not sure you want to sell / give away / recycle some of your cards, you can always keep them sorted in your regular sorting order in a separate box and put that box not with the regular collection elsewhere
* League Points and Prizes may also change depending on the specifics of the event