Errors and updates
If you’ve downloaded a practice file or a score that gets updated later on, how do you know that your file is out of date? There’s a change log. You can compare the date of the file on your device with the date of the change.
Errors in practice files are bound to occur when scanning scores and feeding them to a synthesizer. If they’re discovered, they will like as not get corrected and re-uploaded.
It’s less likely that a score may change; but it could happen.