According to TolkienGateway.com (https://tolkiengateway.net/wiki/The_Book_of_Jonah), Tolkien's translation of The Book of Jonah was planned to be published as a stand-alone book in 2010 by the publisher Darton, Longman, & Todd, but was cancelled shortly before publication for unknown reasons. Some other links with a bit of info below, cited on the TG page:

https://lingwe.blogspot.com/2009/05/mo ... ion-on-book-of-jonah.html
https://lingwe.blogspot.com/2010/02/sometimes-whale-wins.html

Does anyone know much about what this book was intended to include? The full text of Tolkien's translation was published in an academic journal and is very brief, it's five formatted pages and under 1400 words. Maybe a great deal of commentary was planned.