Andrew,
In Applications, Photoshop is listed, but only as a folder. I have now left clicked this to reveal a subset of folders, including PS and Plug-ins. Right clicking PS and then clicking Get Info does show a box Open on Rosetta. I have ticked that. Opening PS from either the Applications folder or the icon on my desktop does not show the plug-in when clicking Automate. The plug-in does show in the Plug-in folder under Applications. I have reported this to Canon.
Best wishes,
Jonathan