The French made a first big attempt at building a canal in Panama in the 1880's
It didn't work because Lesseps insisted on doing a "flat" canal like in Suez rather than one with locks, which would have better suited the terrain.
To be fair, he was no engineer and had been told in Suez that a lockless canal couldn't work and yet it did.
This had major consequences as France abandoned the project to the US and it also had major repercussions in France as there was a massive scandal around the financing of it, which ended as little more than a Ponzi scheme.
Now, what if it did work? The actual engineers on the project were advocating for locks.
Let's say Lesseps gets sick, he wasn't very young anymore and another man like Eiffel takes the lead (he was already on the project), and they manage to build it, what would the consequences be?
And yes, yellow fever, but that didn't stop the French conquering Indochina and if it shows progress I'm sure you can get as many warm bodies as needed