They don't. They're intentionally switched.
False. it doesn't change the fact that the Articles don't agree with the genders of the nouns which they're modify. The Greek grammar is incorrect regardless of whether the text is literal or figurative. This is how the educated reader knows they're looking at a figure to begin with.
The pronoun, "this" (touto), is neuter, and is thus made to agree with "body" (swma), which is neuter, and not with bread (aptos, artos), which is masculine. This is always the case in Metaphors. Here are a few other examples to illustrate.
In Zech. 5:8, "This is wickedness." Here, "this" (fem.) does not agree with "ephah" (to which it refers), which is neuter, but with "wickedness, " which is feminine.
In Zech. 5:3, "This is the curse." "This" (fem.) agrees with "curse", which is feminine, and not with "flying roll", which is neuter, (to which it refers).
In Matt.13:38, "The good seed are the children of the kingdom." Here, "these" (masc.) agrees with "children of the kingdom" (masc.), and not with seed, which is neuter.
What this is showing is that in a Metaphor, the two nouns (or pronoun and noun) are always literal, and that the figure lies only in the verb.