Interesting fact: Octopus is Greek, basically meaning an eight-tentacled sea creature. Its name is functional, just like the names complained about here. It is what it says it is.
I know what 'Octopus' means. I doubt anyone here doesn't. I thought I had already explained that the reason that portmanteau's in foreign languages worked better for the native English speaker than English ones is that in English, when we want to make a proper name for something most of the time we do in fact make a portmanteau's in a foreign language (or borrow it's common name from what it is called locally). The fact that we make words like this in Greek or Latin is precisely the point.
Octopus sounds 'cool', that is to say right and proper to the native English speaker, in a way that 'Eightlegs' does not.
You're not really changing the name, you're just making it so that it doesn't sound like a word you understand the meaning or origin of.
So? Most of Tolkien's invented proper names are built up from stem words in invented languages. Almost all English proper nouns are built from foreign words whether we are talking about place names or personal names. In English, you are just used to hearing borrowed words as proper names as the proper way to name something. In English, you don't normally name someone Purity Spearthrower or Builtlikeaking Strongarms or Giftofgod Furnituremakersson, even if the name you do give to the person actually means that. It doesn't sound right in the ear.
If you want to be amazed by the cool sound of a word, or weird spelling, just keep being ignorant. In fact, be *more* ignorant than you already may be
This borders on being an ad hominem attack. Lexicography is a hobby of mine. I adore etomology. I may not be a Tolkien caliber philologist, but I do try to invent my own languages. I don't suggest using foreign portmanteaus for proper names of creatures out of ignorance that many English words are, but quite the contrary.
Granted, some flavor text along the lines of "Arcanoloths, known to scholars as Raavasta" would be handy.
I'd prefer the reverse, known to scholars as Arcanoloths, and some list of how they might be know regionally and colloquially such Raavasta, Minochmen, Decievers, etc. (that is, assuming Arcanoloths are commonly enough encountered that they'd even have common names, which they might not).
Under that structure, 'Deathrattle Viper' might be listed as one of the creatures common names.