I don't doubt that hearing "vulgar fraction" or just "vulgar" followed by something like one-third is annoying, but how else would a screen reader make clear that you're dealing with the single character format of a fraction as opposed to say, one slash three, for one-third typed out?

I just played with NVDA with several lines that used the three-character numerator slash denominator for one and two thirds, followed by lines with the vulgar fraction character for same.  It reads "one slash three Cuban pesos milk" for what's meant as one-third cup milk and "two slash three Cuban pesos water."  The lines that follow that use the vulgar fraction characters are read as one-third and two-thirds (with no "vulgar" or "vulgar fraction") ahead of it and the word cup is read as cup, not Cuban pesos.

Window-Eyes does the 1 or 2 slash 3 for the three character fractions and reads cup in that context normally.  But, it reads vulgar fraction followed by either "one third" or "two thirds" for the lines that use them.  Cup is pronounced normally.

I'm guessing that if you frequently use vulgar fractions other than the incredibly common one fourth, one half, and three fourths - which I think get consistently read sans any indication of the use of a single vulgar fraction character - that a tweaking of your pronunciation dictionary to drop the "vulgar fraction" part will be needed.
--
Brian

A great many people think they are thinking when they are merely rearranging their prejudices.

         ~ William James