@Phanse17, oh, I’ve got a working solution for this 
I’ve already made a custom node to deal with such rotation problems, so there’s no need to reinvent the bycicle. You can either install my package (zhukoven.com), or download that single ‘Element.GetRotation’ node and place it in the same folder with your Dynamo graph (see attachments).
This is how your helix looks like after some modifications to the graph (also see attachments):
Hope this helps.
Element.GetRotation.dyf (6.7 KB)
Helix mullions placing (zhukoven.com).dyn (165.2 KB)