for the last two years I've been syncing an MfE calendar with my N9. There has been no other MfE accounts on the N9 and the original MfE account on the N9 is still in use - meaning, I have not deleted and re-added the account. I have only one calendar on the server, however, I have created and deleted a few but never used any of them.

Today I have still only one calendar on the server - but 6 calendars on the N9. What seems to happen is that randomly the MfE calender on N9 stops syncing with the server, and a new one is created on the phone. The old entries are still on my phone, but any new ones created on the phone are not synced back to the server. If I create an appointment in Outlook, it gets synced back to the phone, but only to the newest calendar. It *may* be related to the creation of additional calendars on the server, but I doubt it, that each time I would've created a new empty calendar on the server. That's just not how I remember it.

So anyway, I have now two problems.
1) My main MfE calendar (on N9) does not sync with the server.
2) if I were to delete everything from the phone, I would get a new MfE calendar, but it would have lost most of my appointments - and I do not know a way of transferring the appointments from the now inactive MfE calendar on the N9 to any other calendar file.

Any chance of re-activating the sync of one of the MfE calendars on the N9? Deleting calendars? Transferring appointments from one MfE calendar to another?

have you tried looking into /home/user/.calendar/db? It has secure permissions so you would need to copy it out using opensh/ariadnesh I think if not on open mode...