I'm using the Cascade builder.
There is an small issue when exists a story map inside another story map.
Mouse events need to be activate via "double click" on the embedded story map, and then on the text to get the functionality back to the main story map.
In this case the embedded map, the mouse wheel should zoom in or zoom out, but he main story should scroll the text. (Conflict of events)
The swipe control initially doesn't work, so the embedded story map looks just like an image for the regular user.
Maybe adding a frame or the possibility to add some text below the embedded map to explain how to activate and deactivate the second story map.
Could be nice too to "fade" the text of the main story map to show that it is deactivated, or a combination fading the inactive story map.
Nice option to warning when used resources are not properly shared, Private - Organization - Public.