Haven't bothered to read the thread but I have an easy explanation of why eyes could be changeable by the aesthetitian. Glamours are all over the realm right? Sylphs do them, voidsent do them, basically everyone has some capability with glamours even if they are easily breakable. Eye color can be changed by having Jandelaine cast a very minor glamor on your iris. Done, lore friendly as far as I can tell and everyone has more options!