Azusa could have been a PW but not the Wanderer specifically. Or have glimpsed the Kami realm. I suspect WOTC are creating intrigue and mystery to shroud the Wanderer's identity by having Azusa be a PW of old, but Michiko is surely still the best candidate.
I wonder if the Mending awakened Michiko's spark? The fact her spark is so unstable may be because she is half of Kamigawa's Worldsoul. Her spark may keep attempting to return her to Kamigawa without her focusing to remain off-plane.
I adore the art of Minamo on Azusa’s kimono as well. That ice realm is so intriguing as well. Could Azusa have described the Heart of Frost and run afoul of the Yuki-onna? Or is she indeed the wanderer? Seems WOTC is playing up the mystery here. Since Michiko is also a viable possibility.