The reason that Pāli, e.g. Brahmanimantanikasutta, is quite hard to translate.

That's right. It's a bit hard for the translators. 
1. In a normal context, viññāṇa-noun (or the words in the center or end of sutta like that) appears in the same form before, but in this sutta it came in the different form, jānāti-verb. 
2. Pāli is an oral tradition language. The speaker can abstain the word that already spoken in the previous paragraph because he and the listener are knowing it. But when the others, e.g. Ānanda, listen to it, reciting and the explanation, Atthakathā, is required. 
Therefore, even we can read Pāli and Atthakatha, the reciting and memorizing still required.