Some older versions of FileMaker did not reliably list correct results in this part of the DDR. I haven't recently noticed a discrepancy here, but have developed the habit of not trusting that part of the report. What I do, just to be sure, is to a text search for the name of the script. If the script name is not unique or very generic, I might temporarily rename the script to be very unique before generating the DDR and searching for the script by name.
If the only place that I find in the DDR that has this script name is in the actual listing of that script, then I conclude that it is not used in any other part of the file.
But keep in mind that scripts in a different file can use perform script to perform scripts in your file and there is no way for a DDR of your current file to list those references from other files.