I'm... not sure actually! This tool was actually part of a contract I was working on, and it was not needed for isometrics tiles, so I never tested it. I'm not very familiar with Tiled so I'm not sure how they would structure that data. If you do try, be sure to let me know, and I can definitely look into adding functionality for it in the future if it doesn't currently work.
Hey LazyEye- I'm guessing this is a huge request but I'm wondering how possible it is to allow isometric tiles to be converted over to Game Maker Studio 2. As of now they don't import properly because GMS 2 doesn't allow diamond grids from what I've seen.