You can’t think of it that way, there is likely no real “single engine” operating mode. With 12 total motors that can provide thrust on demand, the failure of a main wingtip motor could be compensated for by using some or all of the lift motors along the wing. In this sense it would be far safer than the original twin platform.
Of course on top of that there is the beauty of the much higher reliability of electric motors over internal combustion engines. The absence of ignition, fuel, and exhaust systems means fewer failure modes. The installation of electric quite literally only requires power cables (and some signal wires). No worries of fuels leaks or oil leaks or bad mags or bad spark plugs, or leaking exhaust, etc.
I imagine that the design would also include technology to detect a motor failure that would automatically start lift motors and set power individually to overcome asymmetric thrust.
We can’t think in the same terms when it comes to electric aircraft. As I mentioned earlier, this is changing all the old math.