Hello @mcheruse 
Welcome to the Dynamo Forum!
Whoa, your graph is a pretty wild ride! Pretty much all inputs are wrong in your set parameter node.
And getting an element ID and then Element by ID is the same as doing … nothing.
Let´s take some time and think about what you even want to do.
Do you want to change a type name? I don´t think so, you want to change a type.
Do you want to change the type of a family? I don´t think so, a family contains types. You can add or delete them. How would you “change” them?
What you want to do is to change the type of a family instance, an element.
What you are doing is changing the type name of a type, with a type. That makes no sense.
I´d suggest to start with a “select model element” node. Select one of your railings, see what element you get in dynamo and try to change the type of this element. If this works you can progress and add things to your graph.
And I´m sure there are about 100.000 threads on the internet about changing a type
Finally, this is how to change the type of all railing elements:
I use elements as elements.,
I change the “Type”,
by using a Type.
Kind Regards