There aren't enough bounce cards in this deck to justify using it - only one Merlin, Shapeshifter means you likely won't see it in most games - and not having any cards that cost more than four means it will struggle more the longer the game goes on
Cloud Strife Najeela, the Blade-Blossom is pretty mid to be honest
For Yshtola, it came down to a mix of popularity of the character as well as being a spellcaster, her story and character development offered a wide range of abilities and moments to pull from to lead the deck
Princess Sarah reskin or not, this card is so bad that you might actually make it easier for your opponent to win by playing it, so just dont bother
Sephiroth, Fallen Hero Sephiroth, Fallen Hero brings hellfire to the Commander table
We may even see him sneaking into constructed decks, as he can deal with Diablo - Devoted Herald in some matchups or just be a solid quester in others