This is on a PC, but I'm sure it doesn't matter. I found the bug while investigating what all the XML tags and properties do when creating a custom model.
Example class/models/{name}.xml file:
<ModelBrand>
<PhysicsModel>
<Body
ModelFrame="red"
Mass="0"
>
<Body
ModelFrame="blue"
Mass="200"
>
<Constraint
Type="Hinge"
PivotOffset="(2;0;1)"
AxisLocal="(0;0;1)"
/>
</Body>
</Body>
</PhysicsModel>
</ModelBrand>
In this case, I expect the pivot of the hinge to be offset by (2; 0; 1) in the "blue" frame's coordinate space. However, the pivot is offset by (2; 0; 1) in the global coordinate space instead. If I rotate the model in the map editor, the pivot moves around within the model since the offset is not relative to the model.