Hello, I'm wondering if there is a way to find out who was the last person to modify a form. I see the modify date and create date in the XML Source, but nothing regarding a user ID of any type. This info can be found in a Word document or Excel spreadsheet under the Properties.
There will no such information saved in XFA forms by default. You can determine the current user name at runtime by using a script. Its result can be stored in a hidden field or a specific XML element for later usage:
var userName = event.target.identity.loginName;
TextField.rawValue = userName;
However, Adobe only allows the execute the script above from a trusted context, which means you'll have to create an install a folder level script in your environment.