So they always repeat the same answer, and there is no firmware update. If you have a €€€ CO2 sensor, try binding. I tried faking (with Vasco CO2) but failed. Hope your experiment will succeed
As as a sidenote on the ‘summernight ventilation’, it actually appears to be effective, however, the unit stops cooling as soon as the indoor temperature reaches 24 degrees celsius… So you may not notice that it actually works, and raising the ventilation rate won’t help 
Climarad has confirmed there is no way to change this parameter unfortunately.