I try to be realistic about the books. I'm rereading Book 7 right now, and I just got past the visit to Lovegood's house. Even the second time around, the time spent stuck in the forest doesn't seem too long.
Even so, I realize that the books as a whole have a bunch of Unforgivably Unanswerable Questions. In "Hallows," there were at least two obvious ones: (1) Y-O-Y (That's "Why oh why") didn't Voldemort hide the Horcrux in the Chamber of Secrets (a room he felt fairly certain nobody could ever get into and one that housed one of his greatest triumphs) rather than the Room of Requirement (which he must have known anybody could get into)? And (2) Do you really expect us to believe the Chamber could open for Ron?
Here are some of my favorite Unforgivably Unanswerable Questions from previous books:
Azkaban: With three fully qualified adult wizards who know what Pettigrew is capable of, and one underage wizard who's one of the most briiliant witches Hogwarts has ever seen, AND considering that Pettigrew wouldn't like being handed over to the Dementors, AND knowing that Harry wants to see Sirius cleared, Y-O-Y didn't anyone think of knocking Pettigrew unconscious so he couldn't escape. Surely the unconscious form of Snape must have given them some ideas. Surely "Stupefy" or a blow to the head would have done the trick. Considering everything that happened afterward — even Voldemort himself said he might never have been restored were it not for Pettigrew — it seems like such an idiotic blunder for no apparent reason.
Goblet: So the only reason Crouch did everything he could to get Harry to win the tournament was so Harry could be Portkeyed to Voldemort? Why did he have to do all that when ANY Portkey would have done the job? Harry could have been zapped to Voldemort at the beginning of the year, so Voldemort wouldn't have had to wait so long, AND Harry wouldn't have mastered useful skills like the Summoning Charm and resisting the Imperius curse AND Crouch could have succeeded in his mission without calling attention to himself. All he had to do was say, "Oh, Harry? I left my book in Hargid's cabin. Can you go and get it for me?" To make matters worse, we learn in the fifth book that Voldemort's return didn't go according to plan because so one was supposed to know. Wouldn't it have made more sense for Harry to disappear when nobody was watching, rather than when he had everyone in the entire school watching him?
Half-Blood: So the Patronus can suddenly be used for sending secret messages back and forth? Wouldn't it have been nice for someone to tell Harry this last year? That way, Sirius wouldn't have died.
And while this one isn't "Unforgivable," I'm just curious:
What DOES a boggart look like when nobody's around? And how come nobody ever thinks to ask Moody, who's the one person who's in a position to know the answer?