Consider the sentence, "Most of the apples are fresh." Is it incorrect to say that apples is the antecedent of the indefinite pronoun most?
He didn't mention "Adjective" either, and "Participle" slipped off the Approved List, but that's another story. Of course, this was the 4th century AD, so one shouldn't expect much.
However, as it happens, this list (with "Adjective" replacing "Participle" since around the 14th century) is still what's taught in Anglophone schools as the English Parts of Speech. 4th-century science, applied to a language that didn't exist then.
There have, however, been some discoveries since. One of them is that not all languages are like Latin. In particular, English isn't much like Latin, though it's borrowed about half its vocabulary from Latin, one way or another; however, parts of speech (POS, or Grammatical Categories, as they're called in syntax) are about grammar, not vocabulary, so where the words come from doesn't matter. It's how they're used that counts.
One of the grammatical categories that is very prominent in English is the Determiner. Articles are determiners, and so are quantifiers. In an English noun phrase, determiners are placed before prenominal adjectives:
The first bracketed chunk above is composed of determiners and the second of adjectives; the last word, houses, is the head noun.
Quantifiers include numbers (three of the), indefinites (many of the), and universals (each/any/all of the). They don't all use prepositions, they have very complex syntax, and logically, they are related to Modals and Negatives in that they are Operators, elements with a focus on some other element in a clause. This focussed element is said to be "bound" by a quantifier, and is usually stressed in speech.
Binding is not quite the same thing as modification, a term usually applied to adjectives, adverbs, and articles; this is semantics, not really syntax. A quantifier can bind a word located quite far away from it, and can be moved around without changing the meaning, something that modifiers can't do easily.
And it's not quite the same thing as pronoun antecedents (Latin for 'coming before'), either. They have their own unique syntax.
Executive Summary: Don't depend on Latin when you want to know about English.
No, apples is not the antecedent of most. Most of is a quantifying pronoun.