Can I ask how the knowledge of hieroglyphics impacts the Suez Canal? Just looking at it, it seems like it's something that would have been highly desired anyways, for the same reasons people pursued a Tehuantepec/Nicaragua/Panama canal project.
Of course it was highly desired anyway (IIRC, Napoleon had already schemes in that sense). I have no doubt that it would be built sooner or later. Butterflies may affect timing.
It may be argued that discoveries in nascent Egyptology help drawing attention toward Egypt at large, esp. in France (as, remember, Rosetta Stone was a
French discovery, Champollion and Mariette were Frenchmen). France happened to be the main sponsor and financer of the Suez project.
People were sensitive to such things. Egypt was a to-go place, among other things, partly because all the interest sparked by the Napoleonic expedition and the ensuing decipherment. French Science for you!!!
Maybe without knowlege of hieroglyphs, and the ensuing fascination with Egypt, some investors are slower to answer this call (had already happened for similar things) delaying the whole scheme, or having France capital less promininent in it.
Now, imagine if the Canal is not completed by the time of the Franco-Prussian war, if it happens on schedule.