I've read someone somewhere suggest that Buddhaghosa's insistence on listing and depicting all these cosmological objects (I know the section you're talking about - it perplexed me on initial inspection too!) is because he misinterpreted what "knower of worlds" means... taking it to be literal rather than referring to the "world" of the Buddha's teachings as defined by the Buddha in suttas such as SN 12.44, SN 35.82 and AN 4.45.
"Having understood name-and-form, which is a product of prolificity,
And which is the root of all malady within and without,
He is released from bondage to the root of all maladies,
That Such-like-one is truly known as 'the one who has understood'." (Snp 3.6)
"Whether I were to preach in brief, Sāriputta, or whether I were to preach in detail, Sāriputta, or whether I were to preach both in brief or in detail, Sāriputta, rare are those who understand." (A I 333, Sāriputtasutta)