I can offer only an initial impression at this time ...
First off ... The group was obviously under physical duress from the weather over the preceding 24 hours. They had been soaked from the rains, it was cold enough to snow, and there were strong winds. They were marching uphill toward a prominent local peak the whole time. All the accounts make reference to the group being fatigued / exhausted when they pitched camp the last time (the night before the deaths started happening).
Second ... They were hungry, and there were hints in the accounts that the food they were packing was 'summer' food rather than heavier fare that would have afforded extra calories to help them stay warm.
All these factors set the hikers up to be at significant risk for illness or death from 'exposure' and / or hypothermia.
One thing stood out for me in the English language account I linked earlier:
This golden root would (or should ... ) have been
Rhodiola rosea:
https://en.wikipedia.org/wiki/Rhodiola_rosea
This plant has a long history of alleged benefits in counteracting depression and especially fatigure. It's long been prescribed for reinforcing or stimulating the body in situations of duress or exhaustion. It's also long been touted as helpful in strengthening the body for high-altitude and / or cold weather conditions. The research on these claims has been inconclusive at best:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3541197/
On the final night the group was exhausted, hungry and challenged to spend the night in unexpectedly frigid conditions. They'd collected a bunch of plants recommended for aiding people in exactly those conditions. I strongly suspect they'd have been tempted to consume the golden root they'd collected, even though it probably hadn't had time to thoroughly dry out.
If their golden root had been contaminated (or misidentified, and wasn't even the correct plant) there might be a chance that this could have contributed somehow to the initial illness / death.
Still, the ensuing confusion and resistance to following the leader's advice is entirely consistent with the mental confusion and behavioral weirdness known to occur with severe hypothermia.