Issue: No clear bird's eye view of the structure of a (complex) flow and its components. Solution: How about a sidebar like in Visual Studio where you could see all the variables you define and their metadata (including their scope! once that's implemented), as well as all actions (and their metadata)?
Selecting any of these would give you the choice to edit the metadata or jump to the component in the flow where it is used. Also, enabling drag&drop from the sidebar hierarchy to move variables around to different scopes without having to go to the flow itself to drag the variable actions around. Useful when you have a huge flow to manage.
Issue: Display of complex flows extends beyond screen boundaries and make it impossible to see the whole structure of the flow at one glance to assess the flow architecture. Solution: How about a flow map that let's you zoom in/out of the flow (zoom is user customizable)? Related: How about a navigation tool to let the user navigate the flow by dragging a selection area around the flow map?