Try backing up Seedvault locally rather than remotely. That usually works. Whether it restores correctly, I don't know, because I've never actually tried it.
I've always backed up and restored my app data and files manually. You can export your SMS messages and contacts to backup files. Most apps which store their data locally offer backup solutions (e.g. Signal). It's not clear to me what you'd need to backup from VLC. In my case I'd just need media files stored on my device.
There's no need to root, in fact it's strongly discouraged because it destroys the security model.