Superflat customisation screen have format errors in Australian English / String is missing at crowdin.net

I was making a new world for superflat, wanted to customize it and when the dirt section showed up on " Superflat cusomisation " it said: "Format error: %a ".

Steps to reproduce:
1. Make a new world.
2. Click on " More world options " and click on superflat.
3. Click " Customize "
4. Look at the dirt section.