How did "kitsch" (刻奇) come to stand for emotional contagion in a group?
From the links you shared, the idea is come from the following quotation of "The Unbearable Lightness of Being" - "Kitsch causes two tears to flow in quick succession. The first tear says: How nice to see children running on the grass! The second tear says: How nice to be moved, together with all mankind, by children running on the grass! It is the second tear that makes kitsch kitsch."
And in those 2 Chinese articles it is described more like "group emotional hijacking" than "group emotional contagion".
And yes, I think the author of the article "刻奇（Kitsch）是什么？如何克服刻奇？" misunderstood the conception in some way, then misled others who quote this article.
The author said this: "不揣冒昧的理解是" , means "I presume that", and then expressed his/her understanding of Kitsch.