I realize that your team is hard at work on the Mac version, and there is still much work to do in the UI, but I wanted to give you a suggestion based on the latest Alpha build.
On the Windows version of Logos 4 you have each of the toolbar items explicitly separated from one another (a vertical line between each item: house, book, magnifying glass, command text box. On the mac version those separators don't exist. This led me to believe that the text box was related to library search (given its proximity to the magnifying glass). Additionally, in the Windows version it explicitly states "command" in the text box. It took me some back and forth between the versions to "get" the paradigm. If I was a new user without access to both versions, I would probably be left fairly confused.
Thank you for your consideration!