Me too. The only reason I noticed was cause I think she was the only one who kept changing clothes!
I think the people did not believe in magic or demons as it was all folktales to them now. They were more concerned with Amberle abandoning her post as a chosen one. It took 'some' convincing that the dying tree would continue to release more demons into the world unless they save it. (re-plant it). Thus needing the council to reinstate her as a 'chosen one' and allow her to go on the quest.
That's the thing though. IF they didn't believe in magic or demons, what were they worried might go wrong? What did they have to lose? And whether they believe in magic or not, what other option did they have? She was the only remaining chosen one.
As a council member voting "yes" is the only real option for a couple reasons.
If you believe in magic:
The girl is your only chance. There simply is no other option for saving the tree.
If you don't believe in magic:
What can it hurt to let the girl try some foolish quest? If it somehow works out, "yay! she saved us". (and I voted for her)
vote "no" and there are two outcomes:
Fight a war with whatever is coming (remember, we don't believe in demons at this point)
or
The girl sneaks into the tree and does the quest anyway, saving everyone (only now, you voted against her)