From what I can tell, there's apparently a bottleneck in the later parts of the process? It seems like things generally get through the first couple drafts, but then it all slows to a crawl when they reach Development and every step forward comes over the course of months.
Like, Exigents has been stuck in Development since May of last year for instance, and Across the Eight Directions was in Development somewhere between November 2019 and February 2020, and stayed in Development until somewhere between October 2020 and this January past. It shouldn't take a full year to sort out a second draft work and arrange it neatly, not for a setting book.
Notably, this hasn't been happening with Exalted: Essence. It first appeared on the Kickstarter info tracker on February 2020, and has steadily progressed, got past Development, and is just waiting for the post-development thumbs up before they start editing it all to look nice and arranging the art. And this is a major project at least on par with a splatbook!
EDIT: Yeah, Exalted: Essence cleared Second Draft in a month. Then between late October and late January they completed Development, got past the Manuscript approval, and then settled into post-approval development. Something is definitely fucky with their workflow.