Hi Thibaud,
Welcome to Speckle! Feel free to Introduce yourself 
to the community if you want to! 
Can you please go to: C:\Users\ “YourName” \AppData\Roaming\Speckle\Logs in your computer and locate the Excel folder, inside you will find the Speckle Logs. Can you share it with me? You can send me a private message.
Thanks.