Blizzard often does this naming thingy, calling Manticore looking creatures "Wyvern". Mixing Wyvern, Dragons, Drake.
Gnome / Goblin and the various names for them are used too.
The Trolls in WoW resemble more a "Grendle" or his Southern world counterpart, bloodthirsty, long armed monsters often with blue and green skin, they eat man and are known as wild beasts.
I don't bother with it, because of one simple reason. It does not make sense to bother, all of them, it doesnt matter how they are called by games, folklore or other are completely made up by human imagination.
If the Manticore's in Azeroth are called Wyvern, some smart ass Tauren or other Race tought about a damn name and came up with "Let's call this dude's Wyvern".
Besides... Wyvern are able to talk like humanoids, so they dont seem to bother with their name too.