FF6Tools - Browser-Based ROM Editor

When you opened the file in FF6Tools and it asked you to select a definition of the unrecognized ROM, did you make sure to click the Browse button at the bottom and then select the .json file?

Assuming you did, it's possible the addresses you need to use are different. FF3USME moves the compressed overworld data around as it needs to based on the modules you use. No matter where they're moved, the pointers to those destinations will stay in the same places.

0xEEB212 (File address 2EB212) is the pointer that tells the game where the World of Balance map start. If you look in a hex editor, there'll be two little-endian strings of three hex values each which correspond to the start and stop addresses. For instance, in my project, these values are C1 10 EF 50 32 EF, indicating that the range should be set to EF10C1-EF3250 for compatibility with FF6Tools.

Likewise, 0xEEB21E is the offset for the World of Ruin map start, and 0xEEB22A is the offset for the Serpent's Trench.

Hope this helps.