You make a good point, I keep forgetting she is indeed a half elf, however Viconia is a full drow elf, she looks older and sounds older too, she sounds like an old woman, her voice is unsettling to me. So maybe elves do age.
Inmortal and everyoung elves are mostly a LOTR thing. In D&D elves never have been neither inmortal or inmune to aged (you can take a look to the forgotten realms wiki
https://forgottenrealms.fandom.com/wiki/High_elf). They aged slowly (they are considered adults around 100 years old) and less than humans and live several centuries, of course.
Half elves like Jaheira are the same but with reduced timers (still way more than humans). For example: Shadowheart in game is "only" around 50 years old, because she is a half elf. If she was a true elf, she will be basicallly a kid/teeneger in game at this young age.
