Scanning the thread, I'd like to point something out: The way Wyndle appears to Lift is radically different than how most spren appear (less of a "fairy-like" vibe and interacts with the world in Lift's eyes oddly). In addition, Lift can touch spren and is "partly in the Cognitive Realm."
So, my question is, is Lift maybe perceiving Wyndle differently than others might? Wyndle and Ym's spren have some similarities: Growing plants, lights or crystals. However, Wyndle seems much more mature and much more real.
So, is it possible that Ym is also an Edgedancer, but without the same advantages given to Lift by the Night mother that allows her to interact with spren more easily? After all, Ym never mentioned future-sight, and the "light" could refer to Stormlight rather than Illumination.