Hello casimou :
The problem you are having resembles that from another player who also plays in French on Europe; see Season Journey and Achievement Bug [Solution] - #34 by Mohoo-2785.
In addition, both of you have HC seasonal heroes only. I also play (or played, I suppose) in French on Europe, but with a softcore hero only… and I have not had that problem.
Hopefully, someone at Blizzard is tracking this topic and trying to find common points between all the affected players… and feeding the info to developpers.