It’s possibly been suggested before on here, but adding a section on the app for when you creat a song, you’re able to add multiple tempo and time signature changes through the song.
My band writes originals, and most of the songs we play have tempo changes throughout each song, and sometimes the time signature as well. We’ve been looking at a way of being able to play along to a metronome while having tempo changes in for a while, but there’s nothing out there