it would be a very faint click, but that's a yes. Their clicking can be (barely) audible. They make it when they're happy.
About the flakes... mine have never, ever taken flakes. They live only on the bottom, making surface feeding impossible.
EN's are best fed via putting a frozen chunk of food in their cave (must have lots of caves for them to chill in,) or thawing it in a little tank water and using a pipet.