Animal Skin and Bands of Force item bonuses do not stack

[Suldrun45]

Animal Skin grants an item bonus to AC. The description says that this item bonus is cumulative with bands of force. Currently only the highest of those 2 bonuses is applied.
From what I understand, the Adjust Modifier RE on Animal Skin expects a modifier with the "bands-of-force" slug.
But the slug on the Flat Modifier of the bands of force is "bracers-of-armor". I presume this is a remnant of the premaster^^