Hi @François_Touvet,
Welcome to the community! Nice to have you 
Out of the box, the Client Review Site is specifically restricted to only allow Note content created in the Client Review Site to be seen there. The purpose of this was to keep internal Notes and conversations away from Clients. SG browser created Notes cannot be made visible to the CRS from either the UI, or API.
There aren’t currently any plans to change this feature, it’s locked down pretty tight within the functionality of the CRS to keep everything running smoothly.
An alternative would be to create a Client group user where they can log into your site, and then you can restrict their permissions as needed, but that would incur a headcount to your subscription fee.
Let me know if there is anything else I can do to help!
Cheers,
Beth