Which version of Rhino are you using?
I notice this definition is made with the old version of Kangaroo.
I’d recommend using the new one, which has been included with Rhino since version 6. You can find some example files here.
Also I see you are using these huge List item and Merge components to organize the data - this shouldn’t ever be needed - you can use the Geometry input of Kangaroo to pass lines and keep them in the right order.
For the simulation itself, lines will only be connected if they share a point. So if you have one curve meeting the midpoint of a second curve, that second curve needs to be split into 2 segments so that it has a new vertex at that junction.
Finally, to make sure all the ropes are in tension, you need to set the rest length low enough. One way to guarantee this is to simply set them all to zero, which means they can only ever be in tension.