After executing your sample script "Printers.vbs" the new Printer "NewPDFCreator" still has the default profile assigned!
The problem is, that at this time
[HKEY_CURRENT_USER\\Software\\PDFCreator\\Printers]
"NewPDFCreator"="NewTestProfile"
doesn't exist! The key is not created before following user interaction:
PDF Creator - PDF Print Monitor.Menu.Printer.Printers.SaveButton: Press.
Is there a workarraound (by COM interface) or are you going to fix it soon?