"The Felines named it Avyon. Now this is not the exact pronunciation, nor spelling , but it is close enough. The real name cannot be translated into English"
This trope is a Pet peeve of mine. Sure, a word might not have a good way pronounced well in English, the Khoisan languages being the first that comes to mind. But any word can be translated into English. That's what "translation" means. Some nuance might be hard to translate, but whatever. English is pretty good about at least defining a word through translation.
Sad, for example. If there was an alien word that meant sad, we'd look at the severity. We've got a bunch of words to describe what type of sad, like unhappy, crestfallen, distraught, morose, sorrowful, dejected, depressed, etc. And even if there isn't a word for word translation, something like (being cats and all) let's say the Feline word for sad this time, Vayongraff, means "the sadness one feels when you want to knock things off a table, but there is nothing to knock off." It's still translatable.