Reading https://sailfishos.org/wiki/Application_SDK_Known_Issues#Installer_.2F_Uninstaller I saw I might need to remove my old config, so I did so and uninstalled/reinstalled the SDK, and now I'm . . . getting even less far :( I see just 
"16:35:05: Configuration is faulty. Check the Issues view for details.
Error while building/deploying project harbour-manifold (kit: SailfishOS-3.2.1.20-armv7hl (in Sailfish OS Build Engine))
When executing step "qmake""