Moreover the first attempts to decipher hieroglyphs were in the 14th century, there was an enormous body of examples, and by 1798 they had been connected to Cop

Moreover the first attempts to decipher hieroglyphs were in the 14th century, there was an enormous body of examples, and by 1798 they had been connected to Coptic (a language partially descended for the ancient Egyptian language) and there had been great strides in deciphering them. A rosetta stone for the Indus script might not be enough.