Kolosej: Thank you for the information. When I'm next in these parts, I'll try this variant too.
Trobec: Super photos. Regarding the path to Koštrunovec: you probably went a bit too straight up :-) (directly north of Planina pod Mišelj vrhom). I also climbed quite high because I was looking for the path marked on the maps, but the grass was getting steeper and steeper, and there was no path anywhere. So I descended and found the path from the western side (see GPS track).
Regarding Mišelj vrh, it seems you really went on the red variant. Did you bypass the smaller rock jump on the right side? This direction seemed even significantly more demanding to me than, for example, Škednjovčev's eastern ridge – steep grasses and considerable exposure. Does the terrain higher up, above the place where my third photo was taken, calm down a bit?