How far would it go? Is any old bone enough to satisfy the catch or would it have to be crafted into a weapon? How about if she breaks her own bones and the bone causes additional damage to her soft tissue, does that satisfy the catch, and does it incapacitate her even more than a broken bone would do to someone without the catch? If I scraped the skin of my knuckles in a fight, does that satisfy the catch? Is she incapacitated by touching bones? Could a birds cage made of bones make it impossible for her to escape on her own?
Mostly depends on how you would answer those questions. If she has to be hurt by a weapon crafted from bones, that would be far less than if she was incapacitated merely by being touched by bones.
Though it sounds weird, someone who frequently converses with the dead should not be vulnerable to something that so much symbolizes death. On the other hand, as a messenger she is in between both worlds, sort of belonging to neither. So it would make sense, that the embodiment of one end of that spectrum would be hurtful to her. And since it is sort of a one way street life -> death, it fits.
(Just had to think this out loud
)
For all intents and purposes, 3 is probably a good number to go with. Though I would not just give someone the biggest recovery power they can afford due to their catch. Inhuman recovery is already pretty powerful, and I feel there should be a very good reason for someone to take supernatural and higher (this goes for the other powers as well, of course).
She could also simply take inhuman recovery without a catch. At the inhuman levels it is not really that powerful as to break the game. As a raven shapeshifter, she can already be nigh untouchable, if she so chooses (speed + diminutive size).