I don't understand much from the texts you've quoted, but I know this: Hash functions can provide pseudo-randomness, and are used frequently in cryptographic applications for this purpose. Numbers derived from a random number are considered pseudo-random, but they're treated as equivalently cryptographically secure.

A long series of 6-sided dice results with values [1, 6] can provide the same randomness of a 36-sided dice, taken that they're tested properly. Whether you represent the seed with base 2, base 6, base 10, base 16 etc., it doesn't have a difference (and I don't think you're arguing against of that). Using the hash of the entropy as a seed should also make no difference, because as I said it's treated equally secure. You have to hash seeds and signature values either way in HD wallets.