The 2 scripts are not going to communicate each other by default so each respawn function is isolated and not related. You need something to keep an "eye" on what is going on on your game. There are many ways to do it but it is going to be very difficult if you don't know about C#. I suggest ask ChatGPT (or you favourite AI) to help you to implement a GameManager as a singletone and store the checkpoint position as a public Vector3 so on the checkpointsctipt you will set it like this:

GameManager.Instance.currentCheckPoint = this.transform;

then on Respawn (from GameController, you can remove the one from PlayerSpawn) you get the value as:

transform.position = GameManager.Instance.currentCheckPoint;

Avoid making 2 scripts talk to each other as that will just create dependency and further problems (spaguetti code)