How to use app designer's 'Helper Functions' outside the app, precisely in Simulink callbacks.

I am designing an app that plots the output of a simulink model. For this I am using Event Listener method. I acheived this by adding the event listener directly in the 'StartFcn' of the simulink model and creating a Script for updating the plot.

But I wanted to add the event listener using methods(functions) of the app(Task_1).

The reuired code for now, that I wrote in the buttonpushedcallback is:

            set_param('Task1', 'SimulationMode','external');
            set_param('Task1', 'StartFcn', 'Task_1.addEventListener'); % 2nd line
            set_param('Task1', 'SimulationCommand','AccelBuild');
            set_param('Task1', 'SimulationCommand','connect');
            set_param('Task1', 'SimulationCommand', 'start');

Here in the 2nd line, I added the event listener which directs to the static methods that is declaredin the same app, as shown below:

    methods (Static)

        function addEventListener
            Blk = 'Task1/Scope'; % Task1 is my simulink model.
            Event = 'PostOutputs';
            Listener = @Task_1.execEventListener;

            EL = add_exec_event_listener(Blk, Event,Listener); % Break point1
        end
        
        function execEventListener()
            disp('Exec Works') % Break Point2
            % I just wrote this one line because this method isn't executing at all.
        end
    end 

The problem I am facing here is, when the simulink model strats running, the 'StartFcn callback' executes and enters the addEventListener method(function) and stops at break point1. Now when I press continue, the 'execEventListener' is not executing i.e. the program is not stopping at break point 2 and running the simulink model.

Can someone guide me through this please.

OR

Please show me the right way to use a helper function from app designer to a simulink callback.