So Lilium states that its jet is a tailless design. Now, you can see that it has engines on both sides of the centerline.
Lets imagine that all of the engines on one side fail, how does it counter that asymmetric thrust?
We could speculate that their jet actually has a tail, if you look at the landing gear (It is kinda shaped like a vertical stabilizer - ignoring the fact that I cannot see a rudder there), but even then, it does not seem big enough to counter that thrust.
The winglets could be used as one, but again, I do not see any rudders there.
So how does it counter asymmetric thrust?