there are no "soft" or "softening" vowels. The vowel sounds are represented by SPELLING differences that do not reflect sound. The vowel letter is chosen based on the preceding consonant letter. Russian could do away with either Я Е И Ё Ю by using Ь instead: пьэть, мьач, йэйо, etc. That is, the vowel /e/ can be spelled E or Э depending on the previous consonant. The only anomaly is И,Ы, which do have distinctly different sounds, but they too could be covered by spelling rules.