If I'm understanding it correctly, it's a glimpse at what goes on in Tuonela? Quite different from the most recent depiction of sleeping souls in SSSS. I wonder what drove Minna to change how she depicted it... maybe Tuuri would just be more convenient in bird form 
I'm certainly not an expert on Finnish mythology, but off the top of my head, I'd guess that ye olden Finns did not spend much thought on what bodily form the dead might have in Tuonela ... the lucky few returning from there
in human bodies while everyone needs to be carried there
by normal-sized birds does not exactly promise an easy-to-find, contradiction free answer.
Uhhh unfortunately "they'd be dead if not for me" doesn't really slide off as a good reason for people to be terrible to someone they helped, but oh well. I don't really think "it's okay to do something that would normally scar a teenager for life as long as they don't remember it" is a great line of thought either
Well, yes, certainly. If you
can come up with less terrible measures (or better reasoning, and all the pondering done within the original strict deadline, of course), be my guest. And yes, I'm aware of the "ticking time bomb" fallacy and willing to comdemn the couple policemen it led to think that the rules would not apply to
them and
this particular bad guy (looking at you,
chief Daschner). The difference (to me ...) being that Hannu has
certainty about the consequences of inaction (as far as a mere human can get from the spirits), and is giving a net
gain even to the person he's treating poorly (as apposed to forcing the guy to "take one for the team"). Well, in the case of this
one person he treats (particularly) poorly ...
(Besides, I don't think Puppy-Fox ever mentioned that they wouldn't remember any of this)
... true. I guess I
inferred it from his general impulse to hide his mishap not stopping him from returning the villagers
to life, but it's unclear how he'd rate living human witnesses in comparison to fellow spirit ones. (Or
dead humans, who apparently
still get to talk with The Swan before going into perpetual silence, for that matter.)
Hannu is ultimately rewarded for his poor behaviour and selfishness, what with his parents coddling him and most other villagers tugging their hairs out while he shirks his duties and social obligations in real life. Especially after chapter 6, as I said, the framing of the final scene is that Hannu just imparted some wise advice and his actions in the chapter are fine. But you can also briefly see this right after Mr. Moose's lesson on morality and I think around when Hannu meets the ravens, where he says something along the lines of how he doesn't care about what others say?
Sure, Hannu is a questionable person in general, on account of him being one when circumstances do
not provide him with excuses to doing so. (Or sufficient motivation not to be.) No contest there.
I think it'd have been nice to just see an instance of how Hannu's actions hurt people (in real life, not in the dream), since if the story was going for a realistic "small village" dynamic, it's impossible for his actions to have not caused harm. Even if Hannu learns nothing from it.
His tale of what he used old Pekka's crossbow for
did include
a shot into Riikka's leg ...
and how "everyone got all angry" about it. (No hint at how old he actually was back then, but he
remembers and doesn't seem very sorry about his deed to this day, so ...)
it's hard to wrap your head around why there was a "genuine" Kokko's nest or a "genuine" Tuonela, etc etc...
The nest was needed to establish a rapport from inside the dream pocket to Kokko (supposedly the genuine one), to get the task at hand done. It being there isn't any stranger than all the other props being at hand, from the amulets to The Horn Surma Would Run From. IIRC Mr. Bear
said that the nest was not the genuine one, but some sort of reflection into the dream.
Tuonela was genuine - after all, the villagers' souls
were headed there (aboard overeager birds) when Puppy-Fox established the dream pockets to delay, and eventually prevent, their arrival there. Also, Kokko specifically warned Hannu that he's about to
step out of Puppy's dreams and into (the real) Tuonela.
Huh... can birds recognize faces? I know my birds can recognize me with or without my glasses on, which is pretty fascinating. A lot of animals are very smart, too. Surely they'd also know when people did something kind to them, but considering how humans relied on animals for food or were often violent to them or feared them for diseases, maybe that kind of story's just a lot rarer.
I'm not aware offhand of experiments showing that birds can recognize
faces, but I
do remember that it has been shown that they can find (and use) abstract concepts behind photos they're shown - as in, correctly extrapolate when being shown a
new photo. And of course there's a couple birds that passed the
Mirror Test, thus thought to have a concept of their
own identity.
It made no sense to me at all that (among other things) the Swan runs away from Ville, as if Ville could possibly pose any threat to the manifestation of Death itself.
It is shown later that the neck wound that Hannu and Ville cooperatively inflicted lingers and forces The Swan to rest, so there's a certain cost (of missing other work) to forcing the issue of Hannu and Ville right away. Pain and panic might also have played a role, if I interpret the Swan's facial expression correctly.
