To answer all of you, this is from the Tips and Notes section of this skill.
"Note: It's up to the individual speaker to decide whether animals are animate enough to earn a B-class demonstrative pronoun."
The Boni/Koni difference might be for People/Non-people respectively, as opposed to animate/inanimate. That's my guess. Like if you're referring to a bird in English, you would refer to it as "it" and not he/she (unless you actually know its gender, but that's a different story.)
"Dragon" and "worm" are animate according to the examples in the wiki—in fact we get one Bonys timpys hontes, "that white bird"—so I'm thinking this may be a mistake. Couldn't hurt to flag it for review.
I'd flag it. The previous lesson wouldn't accept "Bony sȳz hontes issa." as an answer. According to the lesson hint, the choice is left to the speaker. Maybe the only good bird is a dead (i.e., inanimate) one?