This console gives you one of each Gwent Card, aside from the Vampire: Katakan Card. You can add the Vampire: Katakan Card with the additem('gwint_card_katakan') command.
The syntax for the addgwintcards command is as follows:
Search our database of 69 Witcher 3 commands...Yes Please
Find below working examples of the addgwintcards command.
This is the only way to use the addgwintcards console command. After executing this command, you'll be given one of each Gwent Card (excluding the Vampire: Katakan Card).