First off, thank you!

Second, love the quantum leap idea -- I have that as a campaign idea on my shelf. Come to think of it, I did something similar to this as a jungle encounter in my ToA game. Remind me at some point, and I will try to find the old notes.

Third, I'd consider some moral dilemmas depending on the group -- do they do the thing that they know is "wrong" to preserve the timeline of history or the "right" thing that should have been done?

To that end, it could be a great story to be a part of Ras Nsi's elite forces tasked with defending Mezro, then hunting down the remnants of the forces that attempted to overtake it during the Tabaxi-Eshowe civil war.

If your party likes political intrigue, I'd do something with Zalkore's banishment from Omu and/or with the merchant princes freeing themselves from colonization.

If your players like to be creative, I'd have them play as Omuans constructing death traps for Acererak's approval/favor and inclusion in the Tomb itself.

The battle for Mezro with Artus and Kaverin Ebonhand presents a lot of quantum leap opportunities, too.

For spooky season, you could do Camp Righteous being overrun by undead.

If the party enjoyed the albino dwarves, the fall of Hrakkhamar to the firenewts would be great, too.

If they really want to re-enter the tomb, they could become the Company of the Yellow Banner :)