I finally got a my reasonable chart result as shown below

And the only thing that I changed in my parameters was the fact of assigning a reference node name to my Setpoint Manager Follow System Node Temperature, which was a blank space before, as shown below:

And that I set it as Node 41 later (like the name of the node) as simple as that.

Thank you everyone for all your help and contribution in this post and the other related posts :)