The Autumn/Winter issue of Scottish Literary Review includes John Herdman's article, "The Witch: David Lindsay's Quest of the Absolute". (Presumably this is based on the talk Herdman gave at the 2020 A Voyage to Arcturus and Beyond: David Lindsay's Visionary Imagination event, which had the same title.)

If you have institutional access, the article can be read at Project MUSE. Otherwise, I can't find a way of acquiring just the one issue, but subscriptions are available via the Association for Scottish Literature.