It turns out that I didn't find Wali al Aswad. She found me.
While the portal I used to get here opened with little fanfare on my end, apparently the other side created quite the spectacle. According to Wali, it was easy for her to spot from atop her wyvern, and she started tailing me soon afterwards. I guess her timely interventions were no coincidence.
She didn't seem very surprised when I told her about the obelisks, their guardians or even that this desert is actually a space station. Either she knows more than she's saying, or experience has grinded the surprise right out of her.