As a francophone, is informatique not supposed to be lexically close to other sciences in -ique to denote it being closer to Computer Science in meaning?
As the académie put it: "science du traitement de l'information"
Yes, this is true. But when you say "je travaille dans l'informatique" (I work in <informatique>), what comes to mind is a developer or a sysadmin. Not someone who does "computer science" (algorithms etc.).
"Je fais de la recherche en informatique" (I do research in <informatique>) would mean doing "computer science".
I am not sure what comes to mind to a native speaker of English when he heard "I work in computer science". Maye the same thing, actaully.
In which case "computer science" would be one "science" where you actually need to add "science" (as opposed to physics, biology, ...)
On the other hand, we have in French "Science de la Vie et de la Terre" - a school subject loosely grouping biology and geology.
As the académie put it: "science du traitement de l'information"