You're right that it is correct in your fourth example, because the passage is definitely speaking of the whole glossarial body. With the other examples-- well, there are those who say it is not good style, it is overblown, to use terminology where term will do, and if the passages are speaking of only a term or two, then I would switch to the latter; however, if they speak of Sextus' broader way of phrasing and defining, then terminology is appropriate. That's how I see it.
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