What are you Trying to Achieve and why would you want to Debug Node.cs?
As far as I know your Debugger does work as intended, Node.cs referees to the Godot specific Node class.
I am new to Godot myself but as far as I know this is exactly what's supposed to happen, since Node.cs is a Godot specific class you aren't really meant to Debug it, you can check the class and it's functions out, but you are only really meant to debug you own code.