How multi-character substitution might explain the voynich’s strange entropy

[quimqu]

I'm surprised that the curves in the last diagram are so close especially up to 3-grams, because your homophonic ciphertext must have a lot more symbols than CUVA and the (random?) choice of homophone must add a lot of entropy... how is it possible?

I attach the function to cipher:

def homophonic_cipher_3c(words):
    letter_map = {c: [c + str(i) for i in range(3)] for c in 'abcdefghijklmnopqrstuvwxyz'}
    out = []
    for word in words:
        new_word = ''.join(random.choice(letter_map.get(c, [c])) for c in word)
        out.append(new_word)
    return out

It's a simple homophonic cipher. First creates a letter map for each alphabetical character (so, each letter will have three different letters to choose randomly during the cipher).

In the cipher, I use alphabetical characters. Imagine that I use voynichese characters instead. I would use only the CUVA symbols. But beware, in order to decipher, it is tricky, as one CUVA symbol might be deciphered also into 3 natural language charaters. So there must be another hidden rule to decipher.