Write the function in a cell as you would have written it in the English version (Ignore the error message). Select that cell and run the macro above. This automatically converts the non-working English function in the cell to a working local one, if there is a function within the cell. Otherwise, nothing happends.
Note that the sub works an a multiple selection (array) as well!
From my language to English
This only shows the translation in a messagebox, since you probably won't have much use of it if it would write over the original, working function...