Can't edit or create appointment when I have a translation file

Hello,

I need your help to solve a strange problem I'm facing with
appointments+.
I am unable to neither add a new appointment nor modify it when in
Appointment submenu of the dashboard using French translation files.

This had been tested with all other plugins deactivated. Of course everything works fine when I delete the translation file. Any idea of what it could be ?

Regards,
Jennifer