Fundy software accepts A-Z letters and input from QWERTY keyboards. To add letters/characters that are not found on a QWERTY keyboard, copy and paste your text from another program, such as Microsoft Word or Google Doc, by following these steps:
1. Click the T icon in the toolbar at the top of the spread
2. Click on the Pencil icon at the top of the text box to open the custom text area
3. Copy and Paste your text in the box

More info can be found here.
***Please note: While you can add special characters to designs within Fundy Designer, you cannot use them in .fsd filenames.