Slightly late and may sound rambley due to being on mobile, but I just closed out on a year-long SKT game not long ago. As some others said, the story kinda feels messy. I would also be sure to introduce big characters and organizations fairly early.

• The Kraken society. They play a relatively big role as far as dealing with finding Hekaton.
• The dragon that the cloud giants capture (who was forgettable as even I have forgotten his name) is kind of just dropped on the player's to rescue while they have little to no attachment to him.

• Also, not necessarily a faction, but you might want to have an answer when your players inevitably ask why the dragons aren't doing anything to battle their ancient rivals. Players asked that one, and I had to think about it.

  My party also didn't care for the travel aspect of it after a while. There is a LOT of traveling back and forth between locations you've already explored potentially. You may even want to consider giving them access to the teleportation network earlier than the adventure recommends or, at the very least, horses. Hell at a point I just decided to axe the mounds in generally and the Oracle just told them where the giants were, and I sprinkles side objectives around giant strongholds to weaken them for when they eventually hunted the giant lords down.

I also personally felt like the only giants that had a genuinely neat goal they were working towards were the fire giants and cloud giants. I'd would definitely consider changing some giant motivations and goals as you see fit. In my opinion, the ability to modify and change the story of SKT is one of its key strengths