A tap tempo feature would be a nice addition. Especially when you not quite sure of the exact tempo, just tap it on the tempo indicator.
That’s a cool idea! I wonder where I would put it or how you would activate it. I’m always very hesitant to add another button to the UI. 
But I have put it on my list of things to think about further. Thanks!
Maybe the tempo display could be tapped multiple times to activate the tap tempo.
Check out this metronome app for reference. Tempo - Metronome with Setlist on the App Store