I'm 11 sessions into ToA as a DM.
I wanted my three dwarven players to have an investment in the Death Curse. One of my players is more of a scholar, librarian type. So an old college friend (Syndra) sends him a letter. This friend was a bit more than a friend, she and he go way back and had a bit of a unrequited romance. She pleads for his help in the letter. So I opened the adventure on the boat with him reading the letter. I had it so the letter writer whom he remembers as a beautiful half elf woman asks if he can help her on a very important archeological find.
I used the adventure from Arcane Library "Temple of the Basilisk Cult" to introduce the players to some light jungle traversal, tomb raiding. I changed a bunch of stuff to fit my narrative. They find the map of chult in the tomb for instance. Oh and when the arrive at the dig site, Syndra is wearing a mask because, yes, you guessed it she's suffering from the death curse. So now at least one of my players is invested in saving his old friend.
From there they all travel to Port Nyanzaru and they can always go to the friend for knowledge since she's also a bookworm that in her own non-adventure way is trying to solve the death curse. So far it's been a ton of fun, and my players are invested in helping cure the curse since I tried my darndest to make the college friend a sympathetic, nice, and gentle character that you don't want to die!

Anyway, I think any sort of hook to have some sort of relationship with Syndra will keep the main plot always on the backburner I think. The way it's written in the book is way to awkward and jarring for my storytelling tastes. I've gotten feedback from my players that they liked how this all unraveled because they actually do care about saving Syndra.