This smacks a little too much of taking advice from Internet comments.
I’ve used SQLite in numerous rich client apps. It’s never been the bottleneck.
Do you need to think about how your organize your data? Absolutely. No DBMS relieves you of that, though.
It’s an app that needs an embedded database anyway. Making your users setup and configure access to a database server for this application would be counter-productive.
While SQLite is indeed underestimated for small-to-medium-sized websites, it’s already recognized as the obvious choice for embedded databases. It would make no sense for a command line tool for your managing music to require MySQL or another giant RDBMS.
Even though the Internet have never been so densely populated with amazing Ninja Rockstar Superstar Experts to guide our path through this computer software industry (which surprisingly enough didn’t exist until AJ, Anno JQuery, ~ 10 years ago); taking a firm step back, looking at your requirements and needs, thinking for a bit and actually selecting the right tool for the job is still a thing. Good on you beets.io for trusting your own judgment.
What kind of mad man wants to store his music library in MySQL?