Hi Robin,
For my environment, I use the Architect 5 installer (PDF_Architect_5_Installer.exe).
Some of the PCs have version 4, and some have even older versions, as deployment of PDF Architect wasn’t automated.
After further testing, it looks like calling uninstall from msiexec would inconsistently remove the entries in WMI’s product class, but never remove the actual program itself.
I’ve committed to removing the product by hand, as it’s not the end of the world if I uninstall it on all the computers by hand.