Would illegally moving cards during a game from the sideboard to the hand/library or vice-versa be a Hidden Card Error or a Deck Problem?

Question

Would illegally moving cards during a game from the sideboard to the hand/library or vice-versa be a Hidden Card Error or a Deck Problem? For example...

1. A player is instructed to shuffle their hand into their library but accidentally shuffles their sideboard into their library instead
2. A player is instructed to shuffle their hand into their library but accidentally shuffles their hand into their sideboard instead
3. A player resolves the second effect of Mastermind's Acquisition without waiting for their opponent to respond, and their opponent wanted to counter the Acquisition
4. A player resolves the Sorcery effect of Fae of Wishes without revealing that the card put into the hand is a noncreature
5. A game is restarted via Karn Liberated and one or both players sideboard, believing they are allowed to do so (the error is caught on the first turn of the restarted game)

How should these types of errors be classified and addressed?

Answer 1

I would say that "Game Play Error — Hidden Card Error" is a better fit for these kinds of mistakes.

While a game is ongoing, the sideboard is really the set of cards "outside the game" for the purposes of wish effects like Mastermind's Acquisition. An improper game action on those cards should be consider a "Game Play Error" and since both that set of cards and the other zones involved are hidden from the opponent, "Hidden Card Error" is the right infraction category.

"Deck Problem" is a "Tournament Error" infraction that deals more with the problem of a player presenting an incorrect deck at the start of the game.