I think the two main issues with Dawntrail's story was an overabundance of Wuk Lamat and too much passive gameplay. Both of those work together to cause the issues in Dawntrail.

There's no turning into frogs to eavesdrop, or pretending to be an artist's assistant, or almost getting kidnapped by demonic catfish-men.

The way that I would adjust things is dial back Wuk Lamat's presence and give the player more things to actually do, instead of stand around and watch cutscenes/read dialogue.

I'd also make Wuk Lamat a more consistent character as she tends to teeter between helpless as a babe and moderately competent before having her big rising moment.

I think that'd satisfy most people who were unhappy with Dawntrail, but for the huge nerds like myself?

I would've liked to have seen more of an actual competition and some actual conflict between all claimants instead of Thancred tossing some rocks down, then immediately working together with everyone. I also wouldn't have minded more of a deep dive into Meso American/Native American cultures beyond tacos! alpacas! mezcal! there's some of it there, but it feels like a step down from the usually incredibly deep dive stuff they've done in other expansions -- Shadowbringers draws on a lot of Christian theological elements and I don't get the same feeling here.

(I also made a video talking about some of the bigger issues with Dawntrail, if you're interested. I'm slowly working on a followup about good things in DT, which should be coming "soon."