The items:
1. 9th arrondissement
2. 11th arrondissement
3. 14th arrondissements
4. 15th arrondissements
5. 16th arrondissements
don't exist in the hierarchy but should.
I have not yet added the children of the arrondissements. You can add the relation via the 'contains' edit feature. It will not become immediately visible on geotree. It needs an update of the search index which happens periodically.