SUGGESTION:

When the plugin cannot rename files (maybe because a file already exists with the name it wants to use) allow the user to type a new file name and click Apply.

Or allow users to choose a rule to add as an extension to additional files.

e.g. If the file is called hello-dolly.jpg and this file already exists – then offer user opportunity to add number sequence or something e.g. hello-dolly-1.jpg, hello-dolly-2.jpg, hello-dolly-3.jpg, hello-dolly-4.jpg, hello-dolly-5.jpg.

And perhaps an advanced option where advanced users can select something like PATTERN “-song-lyrics-###” which gives hello-dolly-song-lyrics-001.jpg, hello-dolly-song-lyrics-002.jpg etc

I think something similar would be very helpful, because the plugin is telling me it cannot rename over 500 images for a client’s site I’m trying to optimise. This would be great!

https://wordpress.org/plugins/media-file-renamer/