Unity terrains and pivot points rotation problems

Question

I'm trying to make a semi-procedural generated map on unity for a game I'm developing. In the game, square platforms are spawned in every direction when the player moves towards them (North, South, East, West, NWest, NEast, SWest, SEast). These platforms contain a flat Terrain as ground so I could paint textures on them and what not. To give the game some diversity I intend to pick a random rotation for these platforms when they spawn (90, 180 and 270 degrees).

The problem is, the pivot point of a terrain is not in the center of it, by default, leading to a really awkward and, in this case, destructive result. I tried to child it to an empty game object with a pivot on the center, but I get the same results.

Does anyone know a way to overcome this problem? I know it is not quite a coding problem, but it's a technical one none the less. I've searched around and the common solution is to child it to an empty, but as I said, it does not work in this case, unless I'm missing something. As always, thank you in advance for your patience and attention. Rui Pires

Note: This is my rotating script, in case there's something I can achieve by modifying it:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class AutoRotate : MonoBehaviour
{
    Quaternion rot1;
    private int a;

    private void Awake()
    {
        a = Random.Range(0, 4);
        rot1 = transform.rotation;
    }
    // Start is called before the first frame update
    void Start()
    {
        
        switch(a)
        {
            case 0: transform.rotation = rot1;
                Debug.Log("case 0");
                break;
            case 1: rot1 = Quaternion.AngleAxis(90, Vector3.up);
                transform.rotation = rot1;
                Debug.Log("case 1");
                break;
            case 2: rot1 = Quaternion.AngleAxis(180, Vector3.up);
                transform.rotation = rot1;
                Debug.Log("case 2");
                break;
            case 3:
                rot1 = Quaternion.AngleAxis(270, Vector3.up);
                transform.rotation = rot1;
                Debug.Log("case 3");
                break;
        }
    }

    
}

Edit:

Adding a couple of images to better portray the problem.

Answer 1

I ended up with a "bandaid" solution adding a localPosition value to the terrain to correct the rotation behaviour:

Quaternion rot1;
private int a;

private void Awake()
{
    a = Random.Range(0, 4);
    rot1 = transform.rotation;
}
// Start is called before the first frame update
void Start()
{
    
    switch(a)
    {
        case 0: transform.rotation = rot1;
            Debug.Log("case 0");
            break;
        case 1: rot1 = Quaternion.AngleAxis(90, Vector3.up);
            transform.rotation = rot1;
            transform.GetChild(0).transform.localPosition = new Vector3(transform.GetChild(0).transform.localPosition.x + 100, transform.GetChild(0).transform.localPosition.y, transform.GetChild(0).transform.localPosition.z);
            Debug.Log("case 1");
            break;
        case 2: rot1 = Quaternion.AngleAxis(180, Vector3.up);
            transform.rotation = rot1;
            transform.GetChild(0).transform.localPosition = new Vector3(transform.GetChild(0).transform.localPosition.x + 100, transform.GetChild(0).transform.localPosition.y, transform.GetChild(0).transform.localPosition.z +100);
            Debug.Log("case 2");
            break;
        case 3:
            rot1 = Quaternion.AngleAxis(270, Vector3.up);
            transform.rotation = rot1;
            transform.GetChild(0).transform.localPosition = new Vector3(transform.GetChild(0).transform.localPosition.x, transform.GetChild(0).transform.localPosition.y, transform.GetChild(0).transform.localPosition.z+100);
            Debug.Log("case 3");
            break;
    }
}

Note: The first child in hierarchy (child with index 0) is obviously the Terrain gameObject.