I don’t think I follow what it is you’re trying to do.
You want ONLY paths that include .au3 and .docx files in them? If so then this is the section of the Filters link above that should apply:
Include specific files only. You have a folder structure that contains a lot of photos and movies from your camera. For some reason you only want to include the photos to your backup. The rule for your backup is +.jpg +.jpeg.
To do this for your file types, in the GUI you’d want to select “Include expression” and put *.au3 then do another “Include expression” and put *.docx.
In your second variant above, you told Duplicati to exclude anything that was a folder. Since exclude rules take precedence over include rules, you effectively ran your job with NO includes.