>>213882073
>Not sure why these would be more "natural",
I meant that they weren't simply created words, but adopted. Well, I think it's a more natural thing to do to adopt a foreign word to describe a new thing/idea from abroad rather than try to construct a new word based on native roots that could describe this thing. I mean, in all languages it works like that so when a new thing/idea comes from abroad, it comes from the name from abroad and this name is used commonly, until the users of the language (or an institution dedicated to keep the language "clean") decide that it just sounds wrong and must be replaced with a native-sounding equivalent.
When it comes to months, remember that Slavic names for months are a bit artificial in this sense so primitive Slavs obviously didn't know the calendar in the contemporary sense. Their names weren't actually names for scientifically defined 30 day periods related to Moon phases but more like general terms for various periods of the year with a large degree of vagueness. You can see it to this day since let's say Poles, Czechs and Croats use the same words for different months, because as I said, it wasn't really something strict.
And this is why some nations, like Russians, when adopting the calendar in the modern, scientific sense, decided to also adopt the western names for strictly defined months - because it was actually something new.