Can you use a standardised feedback master?

When you import slides into a project, the associated Masters come with them. So one way to get the masters you want into a file is to import a slide from a project that uses them.

However, you'll still have to apply the layouts to your existing slides. But that's quicker than redesigning the layouts in each file. 

For future files, you could just make a "set up" file with all the masters and other standard elements you use. Then copy that file to start new projects.