Great map! I don't know much about Zantaric as i've never played there, but I wouldn't get too hung up around specific landmarks. I'm sure most SotE threads have details that contradict one-another, especially regarding stuff that isn't set in the cannon. But if you have a lot of thread ideas for Zantaric I'm sure it will be handy!
As far as an adventure goes you should think about what you want to get out of the thread.
Open threads can be fun if want something light or want to get a feel for a new character. However, I've found they tend to burn out if you don't have a clear destination or plot in mind. Also, the more PCs you involve in a thread the more likely it is to fizzle as life pulls people away.
I'd be happy to throw my characters Kai or Narlis into the mix. Maybe Kai is looking for a plant to reverse his condition, or maybe Narlis is looking to plunder that graveyard you have marked down, or maybe they're just lost?