Agence Eaton called back this morning and have now come up with an explanation.
They originally went via an intermediary based in Paris called Solly Azar. Solly Azar deals with Generali Belgium because their prices are cheaper. However, Generali Belgium are fussier when it comes to documentation. Also, in France, insurance companies give themselves three months to decide whether or not they will actually insure you. (So be warned, if you have taken out a new French insurance policy you may not actually be covered!)
So the outcome is that Agence Eaton will handle the insurance policy themselves, and the actual insurance company involved will be Generali France which works slightly differently. Because Agence Eaton will handle the insurance themselves instead of going through an intermediary, they keep all the paperwork; and were thus able to confirm that they are indeed happy with the English documentation.
The only down side is that Generali France is one-third more expensive than Generali Belgium; but the positive news is that insurance against theft is once again included in the policy. This is because they do not require every part of the motorcycle to be French security-marked. The other good news is that the excess is between €400 to €800, and not €1500 as they mentioned yesterday.
Documentation will apparently be sent for signature later today. But I’m not holding my breath.