These really aren't idioms. An idiom in natural language is a phrase or saying whose meaning cannot be understood without someone telling you what it's supposed to mean (that is, you can't figure it out just by reading the words).

In programming, an idiom is a common, accepted way of accomplishing a task which you wouldn't figure out to do all on your own and whose meaning isn't obvious to programmers of other languages.

I suppose you could argue that certain idioms are more or less universal: using "i" as the index in a loop isn't obvious even if you know a lot of math (why not use j?).

But no one who doesn't program Python is going to figure out the first thing you do in any new Python project is write the line:

    if __name__ == "__main__":
        main()

The fact that it's impenetrable if it's not first explained to you that you should do that is what makes it idiomatic.

Idiomatic also means particular to a specific person or group. If your website is based on comparing the same idiom in multiple languages, that's a good indication it's not actually idiomatic. That's probably just a common task.