any idea what I'm missing?
You missed reading the documentation.
The Install_FAT95 program only changes the built in language corresponding to the drawer the icon was run from. The file system itself needs to be installed manually. (It's not too difficult, though, just copy the fat95 file to the L directory of your boot drive. Done.)
*Using* FAT95 is more difficult. That's why the documentation has been translated to every known language.
