There are three of Wanda’s journals to find in Sea of Thieves. One of them is on Mermaid’s Hideaway, the other at Thieves’ Haven, and the third is on The Sunken Grove. Each of them has a small story where you can read about Wanda’s experiences with the cursed cannonballs, introduced in the Cursed Sails event update. Those journals are still available for you to find and read.
You can find the Mermaid’s Hideaway island at coordinates B and C 13. When you arrive on the island, head towards the center of it and be on the lookout for an NPC named Five Paces Frank. The journal is right next to him near the campfire.
The next journal is also near the center of the Sunken Grove island. You want to look for a small, tucked away cave and enter it. There are no NPCs nearby, though there are a handful of bones and broken items around the location. The journal is nearby.
The final journal is on the east side of the Thieves’ Haven island. Go to the beach at the north portion of the east side and look for a shack. It should look like a shipwrecked ship turned into a small house. The journal is next to the dead campfire.