Still to this day, when I occasionally use Excel/Libre Office Calc I never know wether to write `sum(` or `summe(`. Function names depend on the localization settings of the system I'm working on.
Supporting multiple languages is a problem all right: googling, communication, etc...
It depends.
> So switching by locale should not be a problem?
Until you get an Excel file written in another locale. The coolest one i had was one with Japanese formulas.