For example there is nothing to justify the idea that "kuaneos" was used "to denote a dark shade of blue merging into black" and even much less that it has ever meant "blue-green", as "cyan" means now in English.
The only certain thing about "kuaneos" is that its original meaning was "of the color of the pigment ultramarine blue". The Greek name of the ultramarine blue pigment was "kuanos", from which "kuaneos" was derived in a regular way. Besides "kuanos" there was another pigment frequently mentioned by Homer, "miltos", which was red iron oxide, so that is another color whose meaning is certain.
So "kuaneos" meant, without doubt, just "blue". Homer and other poets did not use the color terms very precisely. In many cases they chose the words that sounded better in that positions of the verse and not those that would have been more appropriate in meaning. Therefor "kuaneos" could be used for any kind of bluish colors, usually for colors of darker hues, because there were few if any objects of light blue color at that time. Nevertheless, the meaning of the word was just blue as a blue paint, without other connotations.
Also in the article, "polios" is said to be "whitish". I do not know where did the author find such an interpretation. There is no doubt that "polios" meant "gray", i.e. the color intermediate between white and black. It means neither "whitish" nor "blackish" but just the middle between white and black.
Some later authors say this precisely, but even in Homer and Hesiod there is no doubt about the meaning. "Polios" is used for iron, for platinum-group metal alloys (a.k.a. "adamant"), for gray wolves, for the hair of aging people who are not yet old enough to have white hair.
The precise meaning of "glaukos" is not known, but there is very little, if any, proof that it might have meant "blue-gray". "Glaukos" was mostly used about eyes, so it might have meant "light blue" as there are few eyes that would suggest the color "blue-gray".
And so on.