recent analysis says she was a knuckle walker. Arboreal ancestry doesn't create locking wrists but the opposite as it pulls not compresses. However her wrist flexors are very similar to arboreal type monkeys.
Richmond, B.G. and Strait, D.S., Evidence that humans evolved from a knuckle-walking ancestor, Nature 404(6776):382-385, 2000. Monkeys that climb trees (ie: orangutans and spider monkeys etc.) also have an angled knee joint like humans.
The problem with analysing Lucy's wrists is that she wasn't found with any, so such analyses are inherently sketchy. Moreover, her pelvis, torso, and legs, are still indicators of bipedal locomotion. And when we look at a more complete fossil of
A. afarensis (i.e., one with wrists):
"Only one partial skeleton that includes both forelimb and hindlimb elements has been reported for Australopithecus afarensis. The diminutive size of this specimen (A.L. 288-1 ["Lucy"]) has hampered our understanding of the paleobiology of this species absent the potential impact of allometry. Here we describe a large-bodied (i.e., well within the range of living Homo) specimen that, at 3.58 Ma, also substantially antedates A.L. 2881. It provides fundamental evidence of limb proportions, thoracic form, and locomotor heritage in Australopithecus afarensis. Together, these characteristics further establish that bipedality in Australopithecus was highly evolved and that thoracic form differed substantially from that of either extant African ape." -
Source +
source.
There are also newly found fossils in Etheopia that show
A. afarensis had foot arches, demonstrating that they were bipedal the the large majority of their lives:
"
The transition to full-time terrestrial bipedality is a hallmark of human evolution. A key correlate of human bipedalism is the development of longitudinal and transverse arches of the foot that provide a rigid propulsive lever and critical shock absorption during striding bipedal gait. Evidence for arches in the earliest well-known Australopithecus species, A. afarensis, has long been debated. A complete fourth metatarsal of A. afarensis was recently discovered at Hadar, Ethiopia. It exhibits torsion of the head relative to the base, a direct correlate of a transverse arch in humans. The orientation of the proximal and distal ends of the bone reflects a longitudinal arch. Further, the deep, flat base and tarsal facets imply that its midfoot had no ape-like midtarsal break. These features show that the A. afarensis foot was functionally like that of modern humans and support the hypothesis that this species was a committed terrestrial biped." -
Source.
In other words, the bipedal motion of
A afarensis is known from more samples than just Lucy, using more than just wrists.
You have provided no sources for this information
Here (en français; you may need to find the English version),
here (where it is used in an extensive kinematic meta-analysis of
A. afarensis), and
here (where it is again used in an extensive overview of both
A. afarensis and
A. africanus, the conclusion of which is that both share all the hallmarks of bipedal motion, and that
A. africanus was likely more arboreal than
A. afarensis).
Again, three more sources that all use the many fossils of
A. afarensis to demonstrate their bipedal locomotion.
There is a chance of error in reconstructing the original pelvis for one.
Indeed. However, we have many other instances of
A. afarensis, allowing us to judge Lucy's pelvis.
Secondly, there are tree dwelling chimps that have a similar angled knee joints so even if she was a biped, no more that a tree dwelling chimp. Also the Blades of her hip were oriented as in chimpanzee (Stern and Susman 1983, p.292.) Features of afarensis hip therefore "enable proficient climbing" (Stern and Susman 1983, p. 290).
Undoubtedly. However, the fact remains that she was bipedal. Whether she was bipedal because her ancestors walked upright in trees (like orangutangs) before descending permanently (like chimps), or because she simply walked upright in the Savannah, is a source of some speculation. The fact remains, however, that
A. afarensis was bipedal.