Possible to Create a Hotkey Trigger with Cmd-Opt-Ctrl-Shift Alone?

I've already know about using re-key mapping by Karabiner-Elements.

Is there any way to use alone for a hotkey trigger in Keyboard Maestro?

What do you mean?

You can trigger a macro when a modifier is pressed using the USB Device Key trigger. After that you could check whether all modifiers are down and only trigger if all are pressed.

Or you can simulate them using Type Modifiers action.

But you cannot effectively use Keyboard Maestro in a low level manner (eg remapping a key to a modifier). Karabiner is the correct tool for that task.

Thank, you.

I've solved the my issue to change Korean and English input using USB Device Key.