To fix in the interim: you can redo the actions (i.e. asking for the creation of calendars on Google) until Google cooperates. Usually on the second try everything goes well.
Although it seems that it didn't export the existing stuff in the N900 calendar to the Google N900 calendar? Is there a way to remove this N900 configuration and recreate the bond, without affecting the other connection I have (where my main Google calendar created a calendar on my N900)