Allows you to work with complex Json objects from your event sheet.
You could just put a condition after the loop that will run as soon as the loop is done. I don't know if you really need an event for this.
Also for commas in a string I would start1 with an empty string. Then when you try to append to it check if its empty. If its empty just add the string. If it's not empty add a comma first and then the string. Then you never have to worry about having too many commas