Can I trigger an event in one module and listen to it in another module?
I don't believe so. I'm not too familiar with multi-module applications, but I think each module operates almost like a separate application - but with shared configuration and models.
With that said, maybe if the modules share an autoloader, you could add an event listener using the other module's namespace. Even then, you'd need to set the listener up in the triggering module - you couldn't just listen for it in the other module and expect it to magically get triggered.