Language Keys - PixelGuys/Cubyz GitHub Wiki
Language keys are recommended to not use shortcuts names and to be as descriptive as possible for some languages.
The first part should be for what needs it.
The second part is mod ID
The third part is component ID (mainmenu, diamond_sword, dirt_block, etc.)
And the last part (optional) should be the ID of the sub-component (ex.: a button name like "singleplayer")
Example: gui.cubyz.mainmenu.singleplayer or item.cubecomputers.computer_case