Variable product import and attributes

It seems that nobody can import csv files with attribute if not importing with first line in English.
The facts (very easy to reproduce) :
Product export CSV is correct when using WordPress in english or french.
CSV Product import does not import columns with attributes (for variable products) if french is set as wordpress language.
CSV Product import works correctly with wordpress in english language or with attributes on first line of CSV is changed to english titles.
A quick look in product_importer.php did not show an obvious mistake.
Probably a hard coding has been made instead of a $variable.
Not very annoying but should be corrected.
Thank you