Plenty of adjectives describe fuzzy-but-narrowly-defined states and yet can both be compared (in the sense of "more X") and have serviceable antonyms. Examples:

Plenty of adjectives describe fuzzy-but-narrowly-defined states and yet can both be compared (in the sense of "more X") and have serviceable antonyms. Examples: blue, happy, inflated, trivial. You actually appear to be touching upon something different, which is that a word describing a state which is in the middle, between two extremes, could actually have two polar-opposite antonyms depending on context. Context is key here and note that all the examples in the article provide that context, e.g. "the AC needs repairing as it's only lukecool". It is difficult talk about antonyms without context for this reason.