As a side note, on this discussion on the safe working, I would give an answer which is slightly different than yours. Here is my take :
"I would consider the safe as having a timeline which is orthogonal to the Bolero's one. Which means, it is totally independent. "Before" and "after" in the safe has no link with "before" and "after" in the Bolero.
The easiest way to play it would be : Next time a player opens the safe (player's time), it finds what has been placed last time (player's time) with no consideration of Bolero's timeline.
A slightly more complex way to play it would be : the safe timeline does not have to be correlated with the player's timeline either... Maybe the object/character has been taken/replaced at another time. How to rule that ? You could let the player decide what they find, roll a dice, or if you (the warden) finds a nice gameplay opportunity decide yourself."