The regular, quick, Doc Import functionality never works for French users. Regardless of whether they click on "Importer" or "Avancé", they are always sent to the Advanced Doc Import page.

The technical source of the problem seems to be the "value" attribute being set by Confluence on the "submit" tags corresponding to each button. Both are in French, and, I'm guessing, the Office Connector has a hard coded boolean condition that compares this value to the English equivalent: "Import". Basically, sending all values not equal to "Import" to the Advanced Doc Import page. If this is true, this problem is occurring for all language packs other than English as well.