Have a look here https://pratiquer.ffmoto.org/sites/default/files/documents/pdf/2018/12/Trophée de France des Classiques de Trial 2019.pdf these were the 2019 trials. No 2020 dates listed yet
3 jours du Cantal (in May); 3 jours de i,Aveyron (May/June) run by MC12; 3 jours de l,Ardeche ( TC La Burle); 3 jours des Vosges (July); 3 jours de la Truyere (October) run by Trial Club St Marnet.
Hope that helps