“I’ve heard (I don’t remember the source) that the word “cancer” stems from idols.”
You heard wrong.
A quick google search will tell you the etymology of “Cancer” The disease and constellation are both named after a crab.
Halevai
“who seemingly have a hard time believing that Chazal,”
You are making the same mistake you made on a related issue. I dont think they have a hard time believing chazal. They have a hard time understanding chazal. Sure it is possible that Chazal meant eating sweet foods will bring a sweet year. But it is also possible that they meant something deeper. Perhaps they meant it as “as a mussar reminder or its a (once-a-year type of) Tefilla.”
iacrisma
“I am not sure an attribution to a fictional character is appropriate to this discussion”
Kabel haemes mimi sheomro.