When trying to save a template with a new/changed formula I got a Formula Error or can not match "".
If you copied the formula from a document or email into the template editor then the problem might be the double quotes or hyphens. Some email tools and applications like MS Word automatically convert double quotes into curly double quotes. Similarly, hyphens (-) sometimes get converted into long dashes (–). Curly double quotes and long dashes are not recognised in formulas.
Edit the double-quotes and/or dashes so that you type those characters in from the keyboard instead of pasting.