Sorry there was a typo in my post! It is 23% not 10%.
The path in my screenshot above got aligned to administrative Terrain Model. Now bikerouter shows this: Half green now.
I am so obnoxious about that section of a path, because on the ground, it is not steep at all, it is just that it passes steep terrain. Before repeating my stance from above, “SAC scale is much more about terrain than it is about paths” (Remember, in the upper grades a path is optional, rather unlikely.) I will have to don my kevlar suit. Please be patient. Said that, steepness may prove useful after all, as in steep terrain a little bit of horizontal difference may produce a lot of vertical difference.
I found that a bit harsh. There are paths existing for hundreds of years and still alive. But a recent walk reminded me of something that bothers me for a long time. Something that makes me wary of adding sac_scale to informal paths. They come and go. On that walk I was out for some PoIs and when placing coordinates on the openstreetmap data I learned, there is a path leading practically up to one of them. It was mapped 8 years ago but only this summer enhanced with lit=no. On the ground: A number of game trails, blackberries, thicket in succession.
The whole of it!