I'm not a native speaker, but "perform this task, for i in {1,2,3}" seems to make sense as a prose. At least it does in French, when translated literally.

personally as a native speaker it has alwaus made sense to me in the sense of saying "for these given constraints, loop while they are maintained" for the arithmetic style for loop, and "for each of these elements" for the more iterator based style.

In python it makes sense but when you have `for(let i=0; I<length; I++)` it makes less sense

"for all i smaller than length, starting at 0". It doesn't really map perfectly because in math you usually don't care about the order, so a for loop actually contains more information than the statement it's trying to mimic.

The same in Polish.

Huh? It's pretty common even in basic college math courses to use language like "for every p in Q". It's not like programming invented this usage.

Also native English: For me it's always made sense only with the loop body, as "for these do that"

Or more straightforwardly, in a way that can be applied to other English constructs, "do that for this group"

It's the same "for" in my head in both those versions.