Longevity of hugelkulture/check logs

Hey guys!
I seem to posting on permies a lot here recently.
The impending move to our new homestead has got me in a fury of planning and thinking, and I had a question.
With hugelkulture and check-log terracing, how do they last? It would seem to me that eventually the support systems would rot. This is more worrisome for the log terraces, though it does apply to hugelkulture as a whole, if those terraces failed there could be a land slide. Our future homestead isnt terribly steep, about 1/3 of is so mildly graded it's basically flat (somewhere between 1 and four feet of drop for 100 feet of distance) but the other two thirds are closer to a 20% grade (most is 15-25 feet of drop per 100 feet of run). I'm worried that after a few years of rot, the terraces would lose their stability. Do you constantly have to rebuild the walls? Or add another infront of each as they become softer? It doesnt sound like a very long-term solution, but i could be wrong.
Secondary, piggy-back question. Almost 100% of the slope is north-to-northwest facing. So the top of the hill could block the sun from the majority of the land until the sun gets pretty high. What could I do with the ~20% slope that is NNW facing?
Thank you guys, I really appreciate it

this may be a bit difficult to read, but hopefully its understandable.
The red contour lines are the highest elevation, and the purple is the lowest. All the lines/colors in between are 5 ft elevation changes.
The arrows are a general idea of water flow when it rains, and then i blocked out the areas with thick, natural-forest level old growth trees. also the two buildings already on the place.

I don't have any useful info on log terraces other than to say that large whole logs will rain fairly strong for a good number of years even with soil.contact, but maybe just plan smaller  terraces?

For what to do with a wooded north facing slope, my mind always go to mushrooms. Inoculated logs could be arranged all sorts of ways all through the woods and let to do their thing. Mushrooms are yummy, nutritious, fairly easy to market, and are reliable trading material with other farmers

I have read some advice against using  hugels to block/catch water because they will inevitably fail if they do that job well enough.
Essentially, hugels are supposed to decay into soil,  plus they are made of wood-enough water and they will float away.

I have built a lot of low terraces,  each level lower than two feet.
When I removed old terrace walls to fix or replace them,  the soil tends to stay mostly in place.
It has been compacted by gravity and is held together by roots.
To be sure you never need to redo the log walls,  I would plant soil stabilizing trees and shrubs.

Part of the answer to the question is whether there is anything planted in front or behind those log walls.  20% grade, while seemingly steep, is really nothing if the slope if forested.  That's pretty much the truth about any hugelkulture -- the soil will not slump if it's planted with deep rooted vegetation -- it's certainly a key principle of swales.  So short term, I'd want to get a cover-crop growing on it ASAP, but long term, I'd want to get trees growing both above and below the check logs.

Best of luck.

William, do you use rock terraces or check logs? Or something else? Either way, how often do you have to do repairs/replacements?

Marco, my only issue with trees is i fear they will shade the terraces too much to grow things. How close should the trees be? Do they need to be on every single step?

I'm trying to figure out if that's where i want my orchard, or if that's where i want to grow veggies. with the north facing slope, im not sure what will work

I used boards and  tree trunks.
No stone,  really.
Terraces a single board high last the best for me.
Logs,  let so,  but they are generally thicker,  and that makes up for it
Multiple logs or boards are the least durable for me.
I build iteratively, so I am usually   re-building before any structural failures occur .

A wooden stake ,being buried,is a prime point of failure for these terraces.
I use scrap metal stakes rather than wooden ones.