Polyphonic Challenge

A polyphonic cipher (see, e.g., here) maps more than one letter of the alphabet to a cipher symbol, which thus cannot be deciphered to a definite plaintext letter. Even an intended recipient would find difficulty in deciphering epistles in such a cipher. I wondered whether codebreaking is possible with such a polyphonic cipher and published a challenge at MTC3.
The challenge was published around 21 November 2019, and many people already succeeded in solving it. Although I had been informed by a private email beforehand that a polyphonic cipher can be solved with hill climbing, it appears to be easier than I thought.
I'm interested to know how these solutions can be achieved.

(By the way, I once lost the plaintext myself. Before publishing the challenge, I tried to decipher the ciphertext with the key. I had to use fragments of the plaintext I could decipher to locate the original text on the web.)