I've noticed when I fought an Evoker, the sound it plays when using its fang attack is incorrect. It plays - 'evocation_illager.cast_spell' instead of - 'evocation_illager.prepare_attack'.

To see/hear this happening, summon an Evoker, listen carefully when it attacks you with its fang attack, then use this command - '/playsound evocation_illager.prepare_attack @p '.

You can easily hear that these two sounds are different, the 'cast spell' one is meant to be played when it summons Vexes not when using its fang attack.

Sorry if this is confusing but I've tried to explain this in as much detail as possible.