Dear Armand66,
Please open CuteSoft_Client\CuteEditor\Configuration\Security folder,
Edit the filenamePattern security of these security file
<security name="filenamePattern">^[a-zA-Z0-9\._\s-\#]+$</security>
Using your own regex for this setting.
For example, set it to ^[éa-zA-Z0-9\._\s-\#]+$
The file name in your post is allowed.
Regards,
Jeff