Friction and Restitution swapped in 3D?

Update: I've been trying to create my own bounce behaviour, but ran into problems with contacts[0].normal not returning the proper values at times. I surrounded the ball by 4 truesync cubes, made it's collider a trigger and attached a TrueSyncBehaviour with:

        public void OnSyncedTriggerEnter(TSCollision other)
        {
            if (other.gameObject.layer != 19 && other.gameObject.layer != 16)
                return;
            var normal = other.contacts[0].normal * -1;

            if (TSMath.Abs(normal.x) > 0.1 && TSMath.Abs(normal.z) > 0.1)
            {
                tsRigidBody.velocity *= -1;
            }
            else 
{
                tsRigidBody.velocity = -2 * TSVector.Dot(tsRigidBody.velocity, normal) * normal + tsRigidBody.velocity;
            }
        }

I added the (TSMath.Abs(normal.x) > 0.1 && TSMath.Abs(normal.z) > 0.1) check to counteract corners, where it enters two colliders during one lockstep tick and would therefore would get sent outside the walls. So far that was working decently, but occasionally, hits with single walls will also return contact[0].normal vectors that trigger said condition. For example, a ball bouncing with the top wall (which usually returns contacts[0].normal = (0, 0, 1)) suddenly returns (0.9, 0, 0.4). I honestly am out of ideas as to why this happens and how to fix it. I tried adding f.e.

if (TSMath.Abs(normal.x) > TSMath.Abs(normal.z)) 
{
        normal.x = TSMath.Sign(normal.x);
        normal.z = 0; 
}

and vice versa to counteract derivations in the contact[0].normal vectors, but sometimes the derivation is so big that f.e. a trigger at the top wall will return a vector with Abs(normal.x) > Abs(normal.z), which would once again lead the ball outside of the walls due to the new normal vector being 90° to what it should be. I also checked whenever a ball was in 2 colliders at once when these things happened by adding the TSCollision to a list on trigger enter and removing it from the list on trigger exit, but the problems don't seem to have anything to do with that, drones passed by when they were in only 1 collider, while they didn't pass by when they were in 2 and the other way around.

I really want to use TrueSync, since it seems to be by far the best fit for our game (many neutral enemies at once, players only controlling their character with click to move to dodge things), but no matter what i try, I can't figure out a way to get a normal elastic bounce with entry angle = exit angle on the TrueSync engine, which is the basis of the entire game. I'd really appreciate any ideas how that would be achievable.

Update 3: Somewhat reliable workaround for now: Surround your colliders with a backup collider (my wall colliders are 1 units thick and the backup colliders are moved 0.5 units towards the outside, so drones have 0.5 units to bounce properly, otherwise backup triggers). Should the drone pass through the normal colliders and hit the backup colliders, reverse their velocity to send them right back in. My bounce script:

        public void OnSyncedTriggerEnter(TSCollision other)
        {
            if (other.gameObject.layer != 19 && other.gameObject.layer != 16)
                return;

            var normal = other.contacts[0].normal * -1;

            if (other.gameObject.name == "Backup")
            {
                Debug.Log("needed backup");
                tsRigidBody.velocity *= -1;
            }
            else
            {
                if (TSMath.Abs(normal.x) > 0.1 && TSMath.Abs(normal.z) > 0.1)
                {
                    if (TSMath.Abs(normal.x) > TSMath.Abs(normal.z))
                    {
                        normal.z = 0;
                        normal.x = TSMath.Sign(normal.x);
                    }
                    else
                    {
                        normal.x = 0;
                        normal.z = TSMath.Sign(normal.z);
                    }
                }

                tsRigidBody.velocity = -2 * TSVector.Dot(tsRigidBody.velocity, normal) * normal +
                                           tsRigidBody.velocity;
            }
        }

Feels ugly, but couldn't come up with anything better. At least it's working consistently in my tests.