That's good, let the sun warm up the home during the day, then let the
heat pump maintain a comfortable temp until you fall asleep then set it
back.

Just keep it cool until until the next afternoon when the sunshine
warms your house back up.

So if they do not mind those cold temps when the experience nice low
wet bulb temps when getting out of the shower on those winter mornings
why even bother setting it back in the first place. Just keep the temp
set low all the time. With a passive solar design, It could even rise
above the set point on a sunny winter day for free.

So now you stayed up all night to basically say why bother making the
system recover from night time set back mainly because it can't without
some extra help. The extra help is sunshine, strip heaters, an
oversized system or a dedicated 'recovery from night time set back'
system.

You have given up on the overnight set back, so we are back to the day
time setback where I already said, "recover while the sun is shining".