Chorus-pro and certificate

hopte this is a right place to put this:

Chorus-pro is limited by a requirement of a specific certificate.
PISTE is a new API, which might not need it. Is it the case ?

Yes this is a new API that replace the former one: Issue 9009: New API PISTE - Tryton issue tracker
It uses Oauth instead of certificate based authentication.
I must say it is a petty from the French authorities to push the new API this hard as it is not allowed for new user to use the former one. They could have planned a longer transitional period.