It's still confuseing who those quincys don't seem to age but the *good* quincies we know all do.
We don't know that's the case. We don't know how (or if) Juhabach has aged over the past thousand years. We certainly don't know anything about the other Vandenreich members in terms of aging or how long they've been alive. We also know nothing about Souken and Ryuuken in terms of age. Souken was always seen through Uryuu's memories, so he's always been an old man. Well, Yamamoto's always been an old man in the story, too, until recent flashbacks (where he was middle-aged and the time period was a good 1,000-2,000 years ago). How long did Souken live for? We have no idea.
And then there's Ryuuken who we've seen in both the current time period and in flashbacks to years before the storyline when Uryuu was very young. Between the flashbacks and the current period, Ryuuken hasn't changed a bit. His features have remained youthful and his hair has (unhelpfully, but suspiciously symbolic given the quincy connection to the colour white) always been white (the anime changed his hair colour in the flashbacks to brown but in the manga, his hair has always been white). So, how old is Ryuuken? Does he age like a normal human? We don't know.
In short, we have no idea if quincies age like normal humans. Uryuu has aged at a normal pace for a human child, but that tells us nothing about whether his aging would suddenly change when he hit adulthood or whether it's a sign quincies all age at a normal human rate.
That's also ignoring the possibility that any (or even most) of the quincies we've seen could have been spirits rather than living humans, in which case, aging (as with all spirits so far seen) probably wouldn't be normal living human aging.