Humming the melody of "The Holy War" previously was a response to the mood evoked by Vasily, the genius musician—it's hard to say whether it was Wang Zhong who brought the tune over or Vasily who was inspired to write it.
Without the emotional buildup, going off-key was inevitable.
It would be best to have a constant tone throughout, like speaking, with a very simple chorus, requiring emotion and artistry.
Moreover, the lyrics must suit the current situation.
The first thing that came to Wang Zhong's mind was the "Cuckoo" by the godfather of Soviet rock, but he quickly realized that the arrangement of "Cuckoo" was very important. In many places, the emotions depended not on the lyrics and melody but the musical expression of the arrangement.
Acapella might not work well.
Wang Zhong had to find something else, and he indeed found it.