Ghoul acquiring abilities

So, the h2p states if a ghoul eats a killing role, they get a night kill, and if they eat a WC role, they get a role check.

What if the role falls under both? Like certain Coven roles (Witch, Warlock, Furie, etc). Which ability do they get?

EDIT: Follow up, what happens if a ghoul consumes a Revenant Corpse, or the VD zombie?

EDIT2: Considering items sometimes work in the graveyard, does the Veil of Shadows change anything?

The general rule of thumb for determining what takes precedence for situations that have different possible outcomes is "what benefits the role/team more?".

In the case of the Ghoul, an extra kill is generally more valuable than an extra check, so the kill is awarded if the target is both a witchcraft using role and a killing role.

Targeting an Undead role that is "less powerful" than a Ghoul (Zombie, Corpse, Wight or another Ghoul) awards a stalk.

Items have no affect on the scavenge ability of the Ghoul.