@roderik have you tried “press and hold”? Simply press the brightness or volume button for 0.25 seconds and a little indicator will appear. While keeping the button pressed, slightly move your finger left or right and you will see the brightness/volume changed.

Yes, I did, will need some more finger habit training to use that one :)

Understood. I think it is a good idea to add a timer to dismiss the volume/brightness bars after inactivity.

For example, it could be dismissed after 3 seconds of inactivity. Sounds reasonable?

Sure!

This has been added. I will test it for a while to see if the disappearance of the brightness/volume bars feels surprising. If not it will be available on the next release (which also includes Mojave support).

EnergyBar Mojave has been released. Get it here.