Pg. 22, middle column, bottom - traveling ethereally, or using greater teleport. I don't think either is possible in 4e.
Pg. 26 - Is the intent really that they see a vision every single round? The 3e version had visions triggered at different times, and the round-by-round visions only started once the big combat broke out.
Trial of the Bell, primary skills says, "See the corresponding sample." What does that mean? I think the skill challenge's wording could be clarified. 6 successes before 3 failures doesn't make sense, because the bell keeps ringing until the party gets through to the next chamber. Perhaps the normal skill challenge format should be abandoned, replaced with a trap of equivalent XP.
Vision of Fear. Actually, when the dragon shows up in adventure 9, his face isn't scarred. Instead, he's wearing a bone mask, like an inquisitor. Except his bone mask is made from four inquisitor liches.
Pg. 27 - Aftermath of the Trial of the Offering. Should a self-sacrificing PC be restored to full HP? It doesn't say how they're returned to life.
Pg. 28 - Maybe shuffle the order a bit. After the end of the first paragraph (...Ragesians and Shahalesti enter), take that section that follows, up until the end of the Scourge vision. Cut that and move it to just before the Facing the Past section. As is, you read about what visions will occur during the encounter, and then you get a vision that occurs at the start of the encounter. It's a tad confusing.
Pg. 29 - First paragraph is missing a close quotation mark. Then there's an accidental line break "crowd quickly -- parts." And again after "The music, please, my emperor." The next line "Do not for me..." should be part of the same paragraph.
When 41 shows up, the text mentions his arms turning into bear claws. Sadly, his stat block makes no mention of this. (By the way, it's weird flipping back and forth, but c'est la vie.) Maybe just give 41 a basic attack where he swipes his claws, and a trait that says he uses the bearclaw swipe on any creature that ends its turn adjacent to him, requiring no action. (He's a solo, so every little bit of damage helps. As is, he's pretty low threat.)
Oh, but I do rather like how you handled putting the new soul into the Torch. One check for each skill is very elegant. Though if the party is wholly untrained in a skill, at level 20 they might expect a bonus of as low as +13, which means spending four standard actions just trying to get the thing working. Maybe lower the DC to 23. That lets them nearly auto-succeed on most skills, and waste fewer turns accomplishing nothing. I mean, as is, they've got to spend, what, 12 or 13 actions at least? That feels substantial enough to activate an artifact. Let's not make it run any longer.
The description of the mural on 41s wall doesn't match what we ended up doing with the entrance to the Heart of History in adventure 12. It's more of a white cliffside with stone dragons guarding a huge doorway.
Pg. 30 - DC 36 skill check to answer a mystery? (At level 20, you might get +10 level, +5 trained, +3 skill focus, +7 ability score, +2 race, and even then you've only got +27, which means half the time you'll fail. I suggest lowering that DC to 28.)
Pg. 54, 55 - The solos here each only deal with half the party at a time. Perhaps they should be retooled as higher-level elites, to speed up combat? Plus, as written, the chorus seems like it gets bonus standard actions, but you never say how many. It might be good to mention in the unicorn encounter that if the PCs dally too long, they'll drown.
Pg. 57 - Okay, this is an odd change from the 3.5 version. Why does Shalosha have a flaming whip and an orb of darkness attack? It's very out of theme.
Also, the 3.5 version had a polar bear companion for Ursus. He's not here, so you need to remove all mentions of it. I think it only shows up on page 28-ish.
Pg. 58 - In the Fall of Taranesti vision, the PCs need to make a save. Why complicate things with dice rolling? Just say that everybody in the combat take 10 points of damage, to simplify things. The combat's already complicated enough.
Pg. 59, right column - Unphased should probably be unfazed.
Pg. 63 - The Gift of Death looks like a duplicate of the Gift of Time. Maybe make Death an aura that creatures cannot enter?