Maybe try the google advanced search function. That gives you options to include or omit certain words/ search criteria. More like a boolean search made easy. Hope this helps.
mac powerpoint location of templates
Unless you select a different location, the template is saved in /Users/username/Library/Group Containers/UBF8T346G9.Office/User Content/Templates. To change where Word automatically saves your templates, on the Word menu, click Preferences, and then under Personal Settings, click File Locations
Go to this folder and see what's present. If you cannot find something and believe you are in the correct folder then show hidden files, can also search that too.
If you provide screenshots can advise on next steps.
Thanks for the suggestions. Finding them was a good start. We operate off Dropbox and somebody (a non Mac user) had clearly synchronised a Word version of some themes into the company's "company template only" folder (but hidden, under about 6 layers of subfolders). For some reason that we still don't know, only Macs found these hidden templates - all the PC users were not affected. It was bizarre. Then every time we deleted it dropbox copied it back again because it was coming from someone else's computer... so now my IT guy has set up a macro to delete it automatically. (because sometimes that's easier than getting our staff to toe the line on what they sync to dropbox!)