Official comment
If you physically rename the file, that is no longer the same file within rekordbox; attempting to load that file would result in a "File not found" error. You would need to re-import and re-analyse the track, any changes to the beat grid, memory points or hot cues would be lost as rekordbox considers it a new file.
It's my advice that if you are making changes to your files because of metadata renaming (you prefer to have things a certain way based on the tags), you should do those changes prior to importing to rekordbox.