Here are the two oddities I picked up on. I hesitate to call them contradictions, but places where the rules deviate from what you've written above.
The first is Intelligence/Perception + Finesse. That matches the published rules for casting a spell oneself. But if you're using an item to do it, you might use Communication + Finesse or Dexterity + Finesse or similar, depending on what the effect is.
The other is that you're still working with ease factors for a mundane craftsman, but they don't have ease factors outside of some vague mention in the core book that never gets used. Instead they have their own equivalent of lab totals to reach: Craft Level. Happily, the numbers match up quite well if you swap in "Craft Level" for "Highest Ease Factor."