My settings are below and should work on any model Kobo.
Dark Mode toggles inverting book and article text to white on black but does not invert images or the user interface.
Invert & Reboot toggles inverting everything, including images, to white on black.
Screenshots toggles whether a press of the power switch saves a screenshot in the root directory or puts the Kobo to sleep; a confirmation message appears to tell you whether you've just turned screenshots on or off.
Translate looks up the highlighted phrase in Google Translate.
Code:
# -----------------------------------------------------------------------
menu_item :main :Dark Mode :nickel_setting :toggle :dark_mode
menu_item :main :Invert & Reboot :nickel_setting :toggle: invert
chain_success :power :reboot
menu_item :main :Screenshots :nickel_setting :toggle :screenshots
# -----------------------------------------------------------------------
menu_item :reader :Dark Mode :nickel_setting :toggle :dark_mode
menu_item :reader :Invert & Reboot :nickel_setting :toggle: invert
chain_success :power :reboot
menu_item :selection :Translate :nickel_browser :modal:https://translate.google.com/?sl=auto&tl=en&text={1|S|%}&op=translate
# -----------------------------------------------------------------------
menu_item :library :Dark Mode :nickel_setting :toggle :dark_mode
menu_item :library :Invert & Reboot :nickel_setting :toggle: invert
chain_success :power :reboot
menu_item :library :My Articles :nickel_open: library: pocket
# --------------------------------------------------------------------------