I think you're changing the wrong camera, here's the path to the witches' cameras
<Camera href="/Cameras/Interface/HireCreatures/Alternative_Upgrades/Shadow_Maiden.(Camera).xdb#xpointer(/Camera)"/>
<creatures>
<Item>CREATURE_MATRON</Item>
<Item>CREATURE_MATRIARCH</Item>
<Item>CREATURE_SHADOW_MISTRESS</Item>
</creatures>
apparently in the Tribes of the East expansion all witches started using the alternative upgrade camera 0_0