Here's some photos of the berms at the lemon tree site. It is a sun scoop shape surrounded by an even bigger sun scoop. The soil is pretty rocky and has pretty much no organic matter. Mostly we seeded it with nitrogen fixers, ground covers, and weeds of all sorts in an effort to start building some good soil.
How many inches of dry earth and wet earth are you imagining right at the very top edge? I'm wondering what the dimensions and orientation of the shoring would be there, so that it is strong enough to hold back all that earth (and the weight of the facade) while only attached to the end grain of the roof poles.
Davin, looking at your most recent drawings that you posted in January, i believe that you switched the duff and subsoil layers. My understanding is that the dry earth layer (which you have labeled subsoil) will act as the heat storage for the wofati. So, we need to insulate the dry earth from the more conductive wet earth layer (which you have labeled topsoil), not from the wofati interior.