I totally disagree.
It's not a power transmission problem.
It's a SYNCHRONIZATION PROBLEM coupled with very high voltages and current.
Synchronization between which components? Generator frequency/phase and landline freq/phase? Between/among multiple generators?
On the assumption that the generators are producing multi-phase AC at a frequency determined by the wind (and at, as you say, very high volts and amps), getting the power transferred should be a difficult but already solved problem -- don't windfarm generators do that all the time?
What are the Germans doing that's so different? Or did they just screw up implementing a known solution?
Many years ago (c. 1980) I designed multi-phase inverters at the 400HP level and we had ways of synchronizing with the existing AC line to pump power to and from the mains. This German issue is 30+ years later. WTF did they do wrong?