Sorry but can't agree. Pops, cracks and and ticks are no arbitrary words, they are direct descriptions of sounds. When you break a piece of wood, it cracks. From the dictionary: "a sudden sharp or explosive noise". Warmth on the other hand, is a description of temperature in the first place.
There is nothing in principle less valid or "less direct" about using the words like "warm" vs "pop" and "tick"in audio.
My point is, strictly speaking, there is no "direct reference" between any word and a sound. That's even in the very rare cases where we use Onomatopoeia. We choose words and terms to refer to things, they are symbols, and it doesn't matter what the word is - what matters is that it can be understood to refer to something specific or defined.
That's why for instance phenomena can even be named after people, e.g.
Aharonov–Bohm effect:
en.wikipedia.org
Or even in sound the Barkhausen effect:
en.wikipedia.org
That shows the "arbitrariness" of terms - we can use any words we want to refer to some definition.
If I were trying to be more difficult I'd say of your reference to "cracks" - hold on, we have cracks in our bathroom tiles, they aren't making any sounds! Clearly there is no consensus that "crack" or "crackling" means anything specifically in terms of sound!
But of course, I do know what you mean, in the context you gave.
"Warmth" also has various definitions, not just temperature. And in audio it is no "less" of a reference to some real phenomena than "ticks and pops" are references to distortions in vinyl playback.
A dirty record is also a nice example of something that could lead to a grainy sound. But in the case you referenced they were reviewing a speaker. How can a speaker cause a grainy sound? If the speaker coil moves against the magnet? Probably not what they experienced with a new speaker.
Strictly speaking speakers can produce non-linear distortion, right? So for instance maybe a driver - woofer or tweeter - pushed too hard operating outside of it's "comfort zone." (E.g. woofer operated wide band so it's also producing high frequencies that distort, possibly combining with tweeter frequencies). "Grainy" may be a reasonable term to describe such non-linear distortion. It might also apply to certain types of "room hash" in terms of a preponderance of close reflections.
As to what exactly might be responsible for an impression of "graininess" or "lack of grain" that's not always easy to pinpoint.
But for instance I did a bunch of comparing Devore speakers (which I loved and was interested in) with the Joseph speakers (I was deciding between the two brands), and with sounds - especially like cymbals, chimes, unamplified guitar high notes, etc - one thing that was consistently standing out to me was the Devores sounded a bit more "grainy" - just a slight sort of granular hash slightly obscuring the purity of the tones, somewhat similar to the slight "hashy sound" that occurs when I introduce more sidewall reflections in my room. Whereas the sound was consistently "smooth" and "clean and pure" sounding on the Joseph speakers.
It's just an attempt to put sonic impressions in to words.
If someone still throws up his hands and says "dunno what you are talking about," then that's why I will often find discussion more fruitful with those who do. (And I found that many of the subjective reviews, and owner reports, of Joseph speakers noted this same quality in the sound.
It's why I personally find exchanges of subjective impressions to still be of use. Objective measurements will always be more precise, but they don't automatically tell you the *subjective quality* of *what it sounds like* - for that we have to discuss this among ourselves. And it's how we come up with terms like "Harsh, warm, screetchy, bright, airy, dark, muddy, thin, boomy, etc").