Wild speculation time! Watch this:
Now, pay attention to what Hector says:
"This unearthly power... Is it coming from that tombstone?"
Tombstone...?
"How consciencious of him. He carved the instructions into stone along with the most difficult visualization."
Wait what? What instructions?
Now, if you use your imagination, you can see that instructions CAN be carved into a tombstone. There is enough space to write in it and etc. But what we see is clearly not a tombstone, and I see no instructions "carved" anywhere. Furthermore, there is this:
"Heed my words, O great powers of darkness! Release to me one of the tortured souls! Let me infuse him with my life-force and awaken him to the world of the living! Immaculate being, appear before me know!"
Now, he says a bunch of things here. First he asks the darkness to release to him one of the tortured souls presumably being kept inside it. Then he wishes to infuse "him" with "life force", and "awaken" him to the "world of the living". This looks like he pretty much is trying to revive something dead, or infuse a dead body with life. One could argue that the fairy statue is it's "dead form" but what about the tombstone?
Finally, this encantation is most likely the "instructions carved into the tombstone". There is no way in hell all of this is carved into that tiny fairy statue.
So yeah, I think they didn't initially plan for this "innocent devil" thing, but actually wanted something more akin to necromancy. But this specific voice over was already done by the time they did the modifications, so they left it in. What do you think?