We don't have logbooks from this time period, but I do concur that they were introduced in 1985. BTW, this was the second "Cornwall II', as by 1985, the company had forgotten about the original Cornwall II that changed from a K-1000 horn to the K-600 horn.
I can say that Tester (Ginny Sanders) is running the Klipsch Museum of Audio History's visitors center, and I saw Claudine Teague in Texarkana a few days ago!