I added some functions and tested this plugin with the version 1.14, it worked.
+ Added log file for the reports
+ Changed the permission report.check to report.admin
+ Changed the command /report delete to /report delete all, if you want to remove all saved reports
+ Fixed some bugs
I have tested this plugin on the spigot version 1.11 and it worked
successfully. Additionaly I added the command /report delete.
Now you can delete all reports.