I’m very happy to report that your suggestion worked for me to solve this problem… although there was an odd twist in the story. In order to try doing a clean install of FCPS2 I ordered replacement disks from Apple. The first time I tried the install it failed at the first audio disk. I just received the second replacement disk and the same thing happened. I got an error message saying that there was no content to install.
It seemed impossible that Apple has sent me two sets of disks that wouldn’t install properly but I thought that I’d at least look to see if the files you mentioned were where they were supposed to be and, sure enough they were and when I copied them into the Proapps folder on my other computer I was able to roundtrip to STP for the first time!
I have no idea why the installation failed but at least I have one working version of FCPS2 and that’s a relief.
Thanks so much for your help,
Chris