Here?
Suggestions - Faithlife Forums (logos.com)
Book Suggestions for Logos (uservoice.com)
or
Logos Book Requests | Faithlife Feedback
Or are we supposed to email FL at their special request email?
Let me guess...The answer is "E" as in E) All of the above???????
For book requests, that is the correct place.
(UserVoice is the old solution we're moving away from. You can always use the forums, but for suggesting a specific book, Feedback.Faithlife.com works better as other users can vote and it consolidates the complete list of suggestions in one place.)