what I did for my game was set up a timer and when it’s triggered it runs the code to fire then sets the timer to a random range and starts it again per enemy instance. Maybe not the most efficient but it was simple haha!
As for the left click variety I should have specified better, I meant specifically some variation in the audio so it’s not as repetitive. And I definitely felt the pain on running out of time myself. Again, great work on your project.