I found the solutions to populate a field with the name of a user as a pickable element with use of the referField function. ( $CS.referField("<FIELDNAME>","users",{url:"/api/v3/users"}); )

Is it possible to get the emailadress (or email_id or primary_email) instead? I tried several parameters but no luck.

It should be like "Email-ID(s) to notify", but we have a usecase where several fields have to be populated by email adresses (concerns right-management, our scripts need the email instead of username). If here only one field had to be filled the EmailCC-Field would be sufficient, but we need up to 4 fields by one time.