You can have Opus log the rename actions and then save the log to a text file that has the old and new names in it.
If you want to do that, you should make sure Opus is set to log "Rename" and "include all files renamed by wildcards" under Preferences -> Logging. Also make sure the maximum number of events is high enough to capture all of your filenames (plus some extra for any other commands which get logged before you save the data to a text file).
Saving the log can be done via Tools -> Output Window, on the Log tab.
Do a test run on some dummy files first to make sure everything is working as you wish.
Here's another thread with a similar question where there are a few other thoughts that might be useful: