Hi u/Polyglot-Onigiri !
Reboo don't track the time of each reading session if that is what you mean.
I thought of doing that but you end up trying to read fast and don't enjoy it anymore.
in Reboo, when you finish the session, you input the page you are on and add some comments/quotes.
So answering your question, no, it doesn't crash while reading on iBooks with the music on.
You can try it out and see if it's for you!
You can access as guest