Definitely cut Salvager of Secrets if you plan on adding the gearhulk, and the rest is pretty much whatever you prefer when playtesting
Whenever a player casts a spell or activates an ability that targets a creature or player, chose a player at random, that player chooses the target of that spell or ability
+2/+2 for legendary creatures is a ton of boost and a definite wincon, and we already have Orzhov decks that play Lyra Dawnbringer and Vona, Butcher of Magan that would benefit
But from among that botched batch of spells there's one that is perhaps the best enchantment to run in your Commander decks: Rhystic Study Hands down one of the best blue enchantments, Rhystic Study triggers with any spell type and doesn't have any of the restrictions cards like Esper Sentinel and Mystic Remora do
So, for now, Fynn, the Fangbearer is stuck being a weak choice, but one that is nevertheless tons of fun