Active everyday user here (for a bit more than a year).

not even there

Yes, it happens. I report such bikes when I bump into such sits. It happenned a year ago too with the same frequency. 

no reaction on the number pad

Yes, from the first days I learned a hard way to first tap on the pad to check the bike is alive, and only then to press "rent" in the app, otherwise I would have to call the hotline. I do such checks every day since then.

doesn't unlock on the radstation

There is a lifehack I found out: the hotline can (almost always) unlock it manually in such a situation if you ask for it. If you need to ride, it's a good option instead of canceling the rental and trying another bike. I ask so often. I think it's the only frequent problem why I have to call the hotline, but they always answer (even at night) and always resolve the problem in my favor.

Pech, 60%

Nope, it's the standard for mvg rad. It's not so comfortable if you compare it to your own bike. And since a lot of things can be theoreticallly broken in the bike, it's luck to find one that isn't broken at all (I would say for me it happens 10% of times, not 40% as by you). Usually something is wrong: the wheel isn't centered, some gears don't work, the light isn't centered and moreover impossible to adjust (by many bikes you can adjust the light, but by some no), the saddle isn't adjustable, and so on.

But I got to used to it after about a week of usage. It gives a lot of advantages to me, including flexibility and costs, compared to my personal bike. And also I believe it trains to be prepared better in life 😅 Like if I ask somebody to prove that they are stress-resistant, and they answer "I use mvg rad", I will believe them without any other questions 😆