It's cited in the Audible series itself (that's where the investigation was originally published:
https://www.audible.com/pd/Podcast/B08JJNYH2J), which is many hours of content, so I wouldn't be able to easily dig that up unfortunately. If I recall correctly, it was a wave of professional instruction that was making its way through either teacher ed or psychologist ed, I imagine of US/UK origin. Do a search for "satanic ritual abuse" and all of the studies around it, e.g.
https://www.jstor.org/stable/3813055By the way, here's one of the psychologists involved in the scandal getting jail time 20+ years later: https://www.ansa.it/english/news/politics/2021/11/11/psychia...
Just to clarify, since I misspoke, the training was not about spotting satanists, it was about spotting symptoms of satanic ritual abuse in children victimized by them.