Currently the only way to change display modes is to open up the mod's settings menu and change it through there.

I think it would be useful to have a keybind to cycle between all of the different modes so, for example, I can bring up the overworld/nether view when I need it without having to pause the game.

At the moment, there is a client command to select the display mode, "/coordinates mode (mode)", but I will definitely add this.