GoodNotes Account
I think it would be very beneficial to implement an account/sign in system. So, whenever users sign in on a new device, all of their documents are already present. Similar to a Google Docs kind of set up. You can sign into your google account from any device and still be able to access your Google Docs.
iCloud can act as an extra layer of security. With this, there'd be less risk of losing documents when switching to a newer device. Often times, in my experience, my documents will grey out and become inaccessible as a result of improper iCloud of which I do not know how to remedy (Wifi connections are stable, everything would be in alignment for an iCloud sync/backup).
Furthermore, as users continue to create documents, they continue to take up their iCloud storage, among other spacious applications and such. I believe a GoodNotes account feature would also be budget friendly to students/users who are not able to constantly upgrade their iCloud storage.
Thanks for sharing your feedback. It sounds like there might be something wrong with your iCloud Sync in GoodNotes if you’re experiencing the problem where documents are greyed out. If it happens again, please report a problem to our support team: https://support.goodnotes.com/hc/en-us/requests/new
Otherwise, iCloud is technically supposed to do exactly what you described.
For other solutions, we’d have to built our own cloud storage, which also would come at additional cost to the user.