I put the folder names back the way they were and I ran the setup program for the 12.5.2 EBF. The setup program recognized that I was trying to install the PBVM on a machine running EAServer as opposed to trying to install Powerbuilder for a developer. But after the installation, the PB Heap Dump summary says:
Sybase PowerBuilder Virtual Machine Runtime Version 11.5.0.2506
So it appears I am back where I started -- that is, running the 11.5 PBVM.
Or maybe just the heap dump summary is messed up. I don't really know. I guess I can run a FileMon trace and see what files are actually being used to run the components.