>> Is there a cell datatype that will work with a fraction that could be set explicit when writing the spreadsheet?
Correctly entered fractions have numeric data type with a number format for fractions:
The problem is with fractions in an Excel workbook that are incorrectly entered as text.
Example how to do it correctly in Excel:
There are some guidelines here if you look at section "Typing a Fraction":
The problem is with users changing the cell format to "Text" before typing the fraction in Excel. That way Excel will store the fraction as text which is not good.
Correctly entered fraction looks like this:
Incorrectly fraction looks like this: