Soul fragments in hand: not a bug, Secret Passage’s card text does not use the word “Draw”, so cards are not drawn, “Cast when drawn” will not trigger.
Original hand not returned to hand does seem like a bug.
as it isnt possible to use your link i can only guss what the hand was. but if your hand is full then passage will attempt to return the cards, they will then not actually be returned since the hand is full, then evocation resolves and discards the spells generated
I believe you are correct, the hand was full at the end of the turn. Since Secret Passage was played before Evocation, and both have an “at the end of the turn” trigger, they would trigger in play order. Secret Passage tries to put the cards back in hand, it cannot. Evocation removes the extra cards from the hand, and then all that is left are the cards generated in hand after Secret Passage was played.
Full link, for convenience: https://hsreplay.net/replay/HZ8NNVfFdcUkKmeb7SihLa
(As far as mangled links users put on the forums to circumvent the “no links allowed” rule, I found this one to be among the least annoying ones. But best to follow the guide on how to post them properly, of course!)