A big, and already mentioned in this thread, issue is when ignorant people start to reimport words from other languages (English these days), and that catches u

A big, and already mentioned in this thread, issue is when ignorant people start to reimport words from other languages (English these days), and that catches up to some extent, even though educated people are using some proper term for decades or centuries. You may end up having multiple conflicting ways to describe the same thing or even a person. A few days ago I saw Hades transliterated as Гадеc in some web comic translation, even though he is usually called Аид for many centuries already.