I feel like I really need to second that. I find this editing system to be really not flexible. It would be really good to understand from a coding perspective and not from a WYSIWYG perspective, how a bottom-up theme can be built. Even though the grid offers good flexibility it takes quite some times for the Pros to get on board on manually adding and configuring widgets rather than setting their own designs directly from scratch on a local ide and with a json manifesto.
Do you plan to open up to this kind of tutorial or all the designers will be forced to work onto your tool?
Looking at the themes structures from FTP, it seems like there's close to no information about it.
The dynamic loading of the content via widgets is very clear, but having another way to edit both widget and the layout system would really be paramount.