Whereas Viconia has been reduced to a leader of a college clique with a midlife crisis and the wrinkles to come with one (she was still young by elvish standards in the originals, and elves live for ~800 years in the setting, with visible aging only beginning at around 600+, so her looking like she's in her forties is completely wrong).
Elves in general just don't look lore accurate in this game, IMO. (There was even a very long thread on this very topic during early access). Iirc, as drow get older, their hair turns yellow-ish and (maybe, like high elves?) they get partial cataracts over their eyes. They don't ever get wrinkly because they just don't age the same way that humans do. Halsin also looks more weathered than an elf should (even though I see why people might appreciate that, it isn't lore accurate). So yeah, there is definitely no reason for Viconia to look as "aged" as she does regardless of whether she's 600 or 300.
There's absolute Lore butchery left and right.
Quasi-Gods are canonically unable to grant powers to their followers(and the Dead Three being back in a weakened status would NOT weaken themselves by further splitting their essence), Jergal being completely out of character(He's the scrivener of Kelemvor but he's there to also make sure Kelemvor doesn't act too zealous or too benevolent while doing his job... he's also known as Lord of the End of Everything, and his dogmas literally say "Never prolong a life unless it furthers the end times", yet he brings back to life adventurers for money), The gods being treated as if this were Eora;
When durge(really bad fanfiction) dies, instead of his/her entire being returning to Bhaal, just some blood seeps out and it shouldn't be happening in the first place cause of Quasi-Gods being unable to grant powers/essence to their followers in the damn first place; Furthermore, Jergal would not bring durge back... it goes against what he stands for as a God and even as a simple scrivener.
Viconia is 346 in current day FR, but they cheekily edited the wiki to make her appear 600 yo(and as you point out, even after 600s, Drow do not age that rapidly); Jaheira should already have Timeless Body as she was way into epic levels, Timeless Body isn't a ritual but Nature granting incredible longevity to Druids through the primal energy they channel through them.
Jaheira says Irenicus fucking used a blood transfusion to steal Gorion's Ward's powers!
Hell even in the prologue, Illithids are so dumb they planeshift into Avernus(It's common knowledge Devils strictly enforce border laws onto planeshifting people who want to be sneaky) being caught into a crossfire, then act as if they lack their mastery of psionics and conveniently don't know how to differentiate between thralls and adventurers!
