And who knows? Others in the past may also have had successful experiences. But they wouldn't go down in lore because a person who has a successful experience wouldn't create this kind of lore.

At least not the prevailing lore—if Zach wasn't making it up, if it wasn't human wishful thinking, the counter-legend of Parnag Fegg helping the lost in the forest could refer to previous successful encounters. I wasn't going to assume that Alma was the only one in history, either. But I agree with you that the other kind of story carried the day. It's rare enough to see other people as themselves without intervening screens of fiction, never mind sentient forests.

this communication and any meaning that's able to survive in a person after it

I just really like this way of phrasing it, as if communication itself is a symbiosis; it kind of is.

The kaleidoscope patterns of the dandelion seeds and the mycelium designs threw me out of the story, a little, in spite of their beauty, because I felt too conscious of their being manipulated visual images.

That's fair; mileage varies. I liked the ordinariness of the images because they felt to me like further evidence of the forest just foresting on.

I took that as her having experienced something of what Alma experienced--though I'm pretty pessimistically sure she's going to shove it into her old worldview.

That was my read, too. Sorry, Olivia.