Snort!! I'm going to be very interested in seeing the source of that voice advising Harry so well. Meanwhile, that's a superb use of the trial to rectify matters in Harry's life that need such action; I do love it that Dumbles was cuaght with his hand very firmly in the cookie jar. Given the changes Harry's already made in how things are done at Grimauld Place, I wonder if Albus is going to have as much effect there as he expects? Too, the visit from Percy should likely create some very interesting ripples as the Weasleys suddenly find they have a very valid reason to distrust Dumbledore. This promises to be quite the wild ride ahead.
It's rather interesting that Harry didn't expose Lucius and I wonder how that little move will affect Lucius' attitude toward Harry.
There are a few errors that rather grate on the nerves. "...This session is to determine Please take your seats.” has a word or words missing, I'd suggest "...This session is to determine this matter. Please take your seats.” SImilarly, “This convenes our meeting." should be “This concludes our meeting." There are some other errors but none as egregious as these two.