These areas were put together and viewed in FModel by setting the version to Unreal Engine 4.27 and using the mappings file from ICARUS. While this works for most areas of the game, it does not work for all. Additionally, a lot of the areas have missing models. See if there is a way to rip the mappings directly from this game, or to otherwise get the .umap files in the Level directory to load properly.
There are more areas than what is currently documented here.
A lot of the islands and various areas of the game have older versions that are hidden in the filesystem. They primarily use assets from Game/Resources/WhiteBox directory, which contain a lot of unused primitive models and early geometry. Some of these areas even have unused segments or variations that are not seen in the final environment.
Starting with Desolatt Island, we get a glimpse at some areas that are completely unused, rather than just earlier versions of areas that are present in the final game.
Overworld
The entirety of Desolatt Island is here...But shift towards the right of it... and you'll find another unused area of Desolatt! It appears similarly to the central area of the island to the left, but is a lot less complete, and more condensed.
Interior Areas
This area seems to be shafted to its own corner next to the previous interior but doesn't seem to be used anywhere.
Lottacoins in its entirety.A boardwalk is placed towards the island's left side, a feature that would not be seen in the final version. It is unknown if it was mistakenly placed there by the developers, as the boardwalk towards the south side of the island is lotta-coincidentally missing.The bridges that connect the two towards is boarded off from viewing from the southern side. In the final version, it is open on both sides.