How are you dealing with the application launch? Do you assume it's already running and just look up the PID, or assume it's not running and start a new instance and then kill it when you're finished, or what?
Have you discovered a key sequence which reliably causes the application to do what you want? Preferably using plain old keyboard input (mouseless input mode is your friend here) rather than using Windows hotkeys.
Have you confirmed that Gobetwino is sending the keyboard sequence you want to the right process when you want it? It might help to prototype that part using a different application that makes it more obvious what keystrokes it has received - I use Notepad a lot for that.