My account got eaten in the purge, but I'm about to start a 12 session expedited run through of the campaign, so here's what I'm changing:
1) The King is Dead. Hekaton is Hamlet's dad, not King Lear. This lets me skip chapter 11 entirely, and expand the political situation at Malestrom.
2) The Throne is Empty. None of Hekaton's daughters have taken the throne, and his brother is serving as regent. The court is in a deadlock that the players can break. Any of the three daughters are viable candidates for ascension, each with their own approach to rulership, and their own strengths and weaknesses. This gives the players true agency in respect to the aftermath of the campaign, allowing them to make a decision with consequences that will shape the fate of a region. (As is befitting of late-2nd-tier, or early-3rd-tier, characters.) The players will be able to back any one of the three without it being a "wrong choice" that leads to the "bad ending".
3) The Oracle is a Woman. Not a magic plot room. Specifically, she's the ex-court oracle of Malestrom. She'll replace Harshnag as your Giant NPC Companion after Chapter 4, and guide the player to the Giant Lords, and eventually to the Malestrom. She'll fill the players in, without spelling out too much for the players, since "it wouldn't be appropriate. My job is to see, not interpret." She can also act as a translator for the characters.
4) No Desecration of Uthgardt Holy Sites. Both in the consideration of time, and also because WOW how did that make it into the final cut of the adventure? That is so inappropriate.
5) No Magic Teleport Shells. If the court thinks smallfolk killed the Queen AND POSSIBLY their King, why would not immediately murder a pack of armed smallfolk who teleported in with a magic conch given only to ranking members of the Court? Instead, the players will gain access to the court by finding a member of the court, and gaining their sponsorship by helping them deal with some previously-low-ranked upstart who is acting out.
6) I'm using the Sword Coast Adventurer's Guide characterization of the Uthgardt, instead of the Storm King's Thunder characterization of the Uthgardt. Because there's nothing really distinguishing them from the Reghed Barbarians in SKT, aside from the animal motif. Also, one of my players chose to play an Uthgardt barbarian, and like, that alone makes them an inappropriate choice for "filler mooks appropriate for a low-2nd-tier party".
7) I'm doing more to characterize each of the three sisters. Because let's face it, the begininng and end of Mirran, Nym, and Serissa's characterization is "the angry one", "the cold one", and "the good one". Rather, I'm going to start by likening each to one of Annam's daughters, who are curiously absent from the adventure itself, but are described briefly in the Monster Manual: "Hiatea, the huntress and home warden; Iallanis, goddess of love and peace; and Diancastra, and impetuous and arrogant trickster. " These three, and their family drama, are at the center of everything that is happening in this campaign, so I'm going to act like it.
Anyway, I hope this sparks some ideas of your own! I welcome any questions, respectful critiques, or additions you all may have.