I have not tested BoxColliders but when you set the scale for your entity base, it will not scale the box collider correctly, to fix it you have to center the CircleCollider and then factor the scale into the radius
this is expected behavior. The Collider actually lives in the PhysicsWorld of Box2D, but is managed and created within your Entity. It is not an actual QML item, which automatically rescales with its parent. It also does not take relative positions over several QML ancestors into account for its position.