Is It Safe to Run on My Only Copy of My Photos?
Work on a copy anyway. Any tool, any day, whenever the photos matter and cannot be replaced.
If it is your only copy, treat it as precious regardless of the tool. Get a second copy onto another drive first. That advice has nothing to do with which software you choose.
Then work in a way that cannot destroy the source: write the organized library into a new folder and compare the two before deleting anything.
Takeout JSON Metadata Fixer does that by default, and reports anything it could not process rather than skipping it quietly. It runs on your own computer and is free for your first 500 photos.