I don't think it's as easy as finding the right box to tick. I imagine that the formulas come with the language version of the software.

However there is a long-winded cheat. The base language (i.e. visual basic) is always in english. So if you are Excel-savvy then open the VB editor window (or record a macro and then edit it..) and type the formula you want in english, and when it writes it to the cell, it'll be translated.

e.g. you want sum (A1:A3) in cell A4
worksheets(1).range("A4").formula="=Sum(A1:A3)"

When it writes A4 will now say Somme(A1:A3) in French. I used this a lot last year, it's obviously a royal pain in the arse and is just a translator; eventually you get used to the formulas you use often.