Function WORKDAY is translated in french as SERIE.JOUR.OUVRE Function WORKDAY.INTL is translated in french as SERIE.JOUR.OUVRE It should be translated as SERIE.JOUR.OUVRE.INTL
Created attachment 122310 [details] Spreadsheet created in english UI of LibreOffice. The text of the two formulas are different in english, but not when opened in french UI of LibreOffice.
It was a mistake in french locale, INTL was missing in some l10n file. See https://bugs.documentfoundation.org/show_bug.cgi?id=93685 Both functions works fine with 5.0.4 FR.
OK.