Not sure if I've understood exactly what you want.
In Simatic Manager you can switch between English and German (under "Extras" this changes the commands and the IO from German to English. I don't have a copy of SCL available at the moment, but since it is IEC 61131-3 compatible I would have thought the commands would already be in English.
What you can't change, of course, are any comments - unfortunately that's probably exactly what you want to change!