We know that to craft an object using Rego or Creo, Finesse is required. However, there's an effect (Duplicate the Mechanism) that allows one to copy an existing device without Finesse.
So if I make a Creo spell to copy an existing object (specifically, a particular theriac), does it require Finesse? It seems like I'm bypassing a speed limit.
YSMV but not if you can perceive and comprehend the object as a whole.
Technically, all Creo spells require an Int+Finesse roll (Ars Magica 5th Edition, page 77), but the ease factor is usually pretty low, like 6.
I dislike that particular spell you referenced, because it suggests it's automatic, because an Intellego requisite. I've never seen that done anywhere else, except for this particular spell. Now, if the item were present before me, and I was doing a Creo spell to create a copy, I could envision not making the finesse roll a stress die. Most magi will have Int of 2 or 3, and a Finesse of 2 isn't all that hard to get, so at that level it becomes a 4 or 5, and you almost can't miss. For the less intelligent magus, they just need to increase their Finesse, or pick an appropriate specialty.
According to HoH:S, the answer is: Maybe.
Basically, a magus who wants to use Creo Animal to create a horse or Creo Terram to create a stone pyramid don't need to roll Finesse unless the details are important in some way (a perfect stand-in of the Duke's charger or a mathematically perfect hemi-octahdren, for example).
Not quite true, natural things (plants, animal) do not require Finesse and Creo always makes perfect example of them. Artificial things require Finesse, but unless the roll botches you get at least a functional (if ugly) object.
If you are copying an object then you seem to be in the second case, and you require Finesse. If you want to make an exact duplicate and not just another object of the same type, the Ease factor is probably quite high.
Or you could put in an Intelligo requisite. That might help.