The names of the various superflat presets are not translated into the new language if the language is changed after the GUI is opened; instead, they stick with the language in use when the GUI was opened for the first time.

To reproduce

1. Change your language to upside-down english
2. Start creating a new world
3. Open the superflat customize GUI
4. Select "presets"
5. Observe that the text is upside down, as expected (2018-09-12_18.43.58.png)
6. Close the GUI and abort creating the world
7. Change your language to normal english
8. Start creating a new world
9. Open the superflat customize GUI
10. Select "presets"
11. Observe that the presets are still upside down, but the rest of the text is normal (2018-09-12_18.46.43.png)

Cause

The preset names are added in a static block within GuiFlatPresets, but they are added with the name already translated (I18n.format is called within the static block). The name should be translated when the text is rendered, instead.