Hi @francois.st-hilaire
Importing an English Canadian family into a project using French Revit is not supported. When the English family is opened in French Revit, the parameters get automatically translated into French (they are standard parameters coming from Revit sw), but the txt type catalog associated with the family stays in English (because it's a static text file).
Revit tries to fill in values for the French family parameters from the text file, can't find any (because the names don't match... that's what the error message is about), and the family gets loaded incorrectly.
This in turn leads to those weird issues with different dimensions in English and in French after import (the dimensions basically get corrupted).
French templates will always throw the errors, because they do not contain any of the CISC families (they need to be imported, which fails), while the Canadian templates do contain some CISC families already, so the problem wouldn't be visible there right away - not until you try importing additional types from the English txt.
Have you checked out this article yet? Country specific structural steel sections families cannot be used running any languages for Revit
