It's one thing to learn the subset of English that makes up the syntax of a language (for, while, if) and its standard library (map, filter, tree). Heck, in a lot of cases the meanings of these are sufficiently technical that even native English speakers have to learn what they mean (though they have an easier mnemonic "hook" to hang this new meaning on, of course).

It's quite a different thing to suggest that in order to program one must become conversationally fluent in English. It's like the difference between memorising all the articles and prepositions (closed list, easy-ish) and memorising the entire dictionary of nouns and verbs (open list, much harder).

So I'd say to go ahead and translate the "nouns and verbs" (class names, variable names, method names).