Hey Jake - Where have you heard Sepp talk about planting fruit trees at 45 degrees in a hugelkultur? Every time I have heard him talk about fruit trees and hugelkultur he seems pretty adamant that you should not plant fruit trees in hugelkultur. This is because as the wood decomposes into humus it it shrinks in size. This would destabilize fruit trees in a hugelkultur over time and potentially lead to them being blown over and up rooted.
He does recommend to plant berry bushes at a 45 degree angle into a hugelkultur or the side of a berm, this is a rather ingenious suggestion. This way when the plant is loaded with fruit it is weighted down a bit and can be harvested right at chest level. Raspberries for example are then out of the way for most of the year but when they are heavy with fruit they drape down right at chest level. Is this what you are referring too?
Swales are agroforestry systems, trees can go right into them. The difference is that they don't have the woody core, which breaks down over time. If the decomposing wood is underneath a tree it will likely destabilize the tree and it very possible that the tree is up rooted during a strong wind.
Just to clarify the first illustration is the "correct" approach, the following image is the "incorrect" approach, as labeled in sepp holzer's Permaculture.
I can't see clearly enough in your screen capture to be able to tell anything. I wouldn't be surprised if this is something Sepp has tried before, but I didn't see any trees in any hugelkultur at the Krameterhof or the Holzerhof. Berry bushes absolutely, this is what the Hugelkultur at the Krameterhof are used for now. If there were fruit trees in hugelkultur at some point they are either not there anymore, or the hugelkultur is so small that you can't tell it is there. The illustration clearly has fruit trees above and below but not in the hugelkultur.