Firstly I won’t add to the speculation because I have no idea how or why ED is missing other that I suspect an accident, somewhere in the general vicinity of her last photo.
Reading through all of the post there is one issue that I see as factually incorrect which is the light levels. I mentioned this before but I think it is probably buried in the first thread.
Spain - Esther Dingley, from UK, missing in the Pyrenees, November 2020
I’ve added some images and links which I hope will be helpful.
I agree the valleys are darker and that fading light is risky in the event of a mishap but I do not see darkness as a primary cause.
It was not dark at 5.30pm.
I took this photo from my house (100km away) just after 5.30pm this evening. The pyramid-shaped peak is the Pic di Midi Bigorre which is about 50km NW of the Pic do Sauvegarde.
The other photo is a webcam from Plateau du Clot (5000ft) Pont D’Espagne at about 6pm 5000ft. This is over to the west.
Cauterets, vos vacances à la montagne été comme hiver.
I’ve tried to keep this brief so if you have any questions, chip in.