There was a situation in London that I think would be worth covering and getting some more guidance on. The actual call resulted in a deviation, but goes as follows.
Anna has a few cards in her graveyard and has 1 creature card (a
Bloom hulk) in exile, tucked under her graveyard. She casts
Finale of Revelation with X=10. She shuffles her graveyard (and the exiled card) into her library, then draws 10 cards. After drawing, she casts and resolves an
Elite Guardmage, drawing another card. After drawing this card, she realises that she drew the Bloom hulk while resolving Finale of Revelation.
Firstly, this cannot be HCE as the identity of the original object was known to both players at the time the infraction was committed. Therefore we're left with the options of GRV - Backup, or GRV - Leave as is.
Backing this situation up would get super messy, as when we're randomly putting cards back on top of the library, the Bloom Hulk could still be in the hand, and we just end up with the same problem we started with (unless we choose a card to exile, in which case, that's super messy).
Leaving this state as is is the best supported option in policy, however I don't feel we end up with a good game state. Anna's opponent used a removal spell on the creature (
Wanderer's Strike) to exile it. If we leave the state as is, we have one player who has spent quite a bit of mana on a removal spell that hasn't really done its job, and another player with the chance to cast a creature that should not legally be there.
The fix we ended up applying was to first ensure that there was only one copy of the card in the deck, have Anna reveal the Bloom Hulk and place it into exile, allowing her to draw another card. This deviation felt the most comfortable and least disruptive to deliver, and resulted in a proper game state again.
I understand this may not be the sort of situation you're looking for, as we have a fix supported by policy (Do nothing), however I thought it was worth noting.