^ I had that same problem. Stupid design of the calipers with the push pin holding the spring which also holds everything else in. I had to weld that push pin on the caliper so it did not come loose again.
The brakes will get very soft when the car is running, what you don't want to have happen is the brakes going to the floor or have the car slowly slow down when you quickly press on the pedal. go for a short test drive, making sure your e-brake still works first, just to see if your brakes feel good.
Like others have said, when the car is off, the pedal will become very hard. This is normal. Because you have witnessed this, you can rule out a bad booster
Which wouldn't make the pedal feel soft, only hard.