Hello my friend!
In your process model, the first activity you have in the child process is a script task, and this script task is the one that sets the “Repeat” variable to “on”.
When this happens, it automatically activates your “Boundary event”.
If you want, you can try to do a test by putting a user task just to lock your process between the boundary event and the call activity, so when your boundary event is activated, you can be sure of it and you will lock your process with this user task and you can better understand the behavior, looking at the current state in the parent process, and in the child process, like my example below:
William Robert Alves