I propose to complicate the kata with double encryption after the first encryption +1 calculate the number of letters encrypt the message +n

first option
n = len([хь, о, м, у, х, в, у]) % 49
input хьо мух ву >> х1оь нуьхь гуь >> ъу тчщ ич

if the letter length is even, first +n then +1 encryption

second option
n = len([хь, о, м, у, х, в, у, 1]) % 49
input хьо мух ву >> ъу тчщ ич е >> 1ч цюяь ню къ