That glossary never helped me, FWIW. The only way I learned a small part of the vocabulary is by listening to more IEMs and by comparing them. But then, I am not that bright!
@Argus,
I think by “flat”, you mean “not engaging”, “not fleshed out sound”, “not warm” … which won’t change with burn-in. After all, they are supposed to be B2 with bass. I hope I’ll get mine by this weekend.