I actually gave links way back i wpuld post them again but i am at work now but if you will be patient tomorrow i will give you all the material you need
Fine, but if you just link me the wiki and don't actually read the citations, I will be disappointed (though not surprised).
I understand RA Salvatore released a book that had some additional Viconia "lore" in 2005, but I'm not aware of any actual mention of her age in any work.
Personally, I think it's more purposeful uglification by the woke devs.
Same with Jaheira, really. They could have kept her young with magic despite her ancestry. The game even tells you this. But at least it's believable and understandable in her case.
Again, it's was a mistake to include characters from the original games. But 5E lore is garbage that mostly digs up 2E and 3E lore and gives its own crappy spin on it, so it's consistent. And BG3 was ruined ever since Wizards decided to use the novelizations, which I doubt most people read, as canon.