Wow, surprised the last reviewer didn't totally kill KaOS, that one is actually pretty positive for him.
And the major bug he mentions in the installer is luckily fully known and linked everywhere as part of the Known Issues.
But, ofc, that is not an excuse, a fail is a fail. That is the price you are going to pay for being the first who (needed to) used a brand new installer.
Only by releasing are you going to find out, internal testing is only going to get you so far.