I don't have illuminated buttons (yet), so I'm spouting forth from a position of ignorance. (Maybe there's a job for me in government...)

You say "it saves the settings over power cycle. And it uses different settings for headlight-on and headlight-off."

And "button brighness cuts in half when the headlights are on".

Either there are independent settings, or the headlights-on value is dependent on (namely half of) the headlights-off value. Or am I misunderstanding you?