A ten digit number was never a valid HIN. The original system used 12, and most boats now use 15.
The catch is at the time of manufacture of the boat you are looking an HIN was not yet standard on all boats built in France.
It seems Amel put HINs on some boats and not others. Ours, for example, has none. Well... kind of. All the paperwork for our boat lists a 12 digit number in a very non-standard format as the HIN--but it is not on the hull anywhere. But nobody has ever noticed or cared...
But all that aside... insurance will be not problem. Contact Scott Stusek (sstusek "AT" pantaenius.com) in Annapolis. He can give you information about Pantaenius insurance. They know and love Amels. Nobody has any trouble with getting their boats insured with a number of various yacht insurers.
Annapolis, MD, USA