As of my last update in 2023, Kei Coffman is not widely recognized as an established author within the public domain. It's possible that they are an emerging author, an indie writer, or someone who writes in a niche that hasn't gained widespread attention. If Kei Coffman has begun to gain prominence more recently, I would not have any information on their work due to the cutoff in my knowledge. For the most current details, it would be best to search for information on platforms that provide updates on new and independent authors, or check the latest databases and publications that track authors and their books.