I also ran into some bugs with that quest, I have a new save, and when I asked about healing magic vs potions, Fern brought up an encounter with something in the forest before I'd left the village, and afterwards, Arthur was busy with samples I'd never brought him. On day 3, he finished processing the samples, and told me to look in the deep forest, but nothing popped up in my quest book, and I can't go to the deep forest.
Edit: Once I reached level 2, I did actually get to the deep forest, and the quest seems to have started properly. Unrelated to that, I have some thoughts on the stats. Appearance says it increases merchant discounts, but it doesn't do that. Your most recent devlog says that attacks and teases use the same aim stat, so what does Charm do? It feels really weird to have Perception and Observation as 2 different stats, since the names imply that they're basically the same thing, Luck would probably be a better name for what Observation does.