Is there any way to get detailed report of who is running CSOM/JSOM scripts in SharePoint 2013 environment and what those scripts are doing?
CSOM is using web services so you would have to look at the IIS logs to determine the operations. But I am not sure is there way to determine what is the source. (ie. you might be using some other software for migration/moving content around that might be using the web services as well)