Roon updates the metadata in your collection periodically, and analyzes your audio files on import, but you can always force Roon to do it again. This can be done using either the Album Editor or the Track Editor. For example, in the Album Editor, in the Your Files section of the edit menu:

You can re-scan your music for changes to file tags and embedded artwork, which will also scan for cover art saved in the same folder as the album. You can re-identify your music, which attempts to match the album in Roon's database just like the first time you imported it. You can re-analyze your music for corruption.