I tried to use “alt+f” followed by “e” to reach the export option in the file menu. Instead, the focus is moved to Exit. Repeated “e’s” lock the focus on New from template instead of cycling the menu between “e” options as it should.
A quick test in the other menus gives similar unpredictable actions. So chances are that this already is on a to-do list 
I don’t have access to a Windows machine here at home so I can’t test this until the other side of the weekend, but I guess the problem is that there is more than one mnemonic in the File menu that uses the letter E. I’ll take a look at this when I can.
I’m on Windows and I can reproduce this. Also, Alt-F X does nothing for me (it should exit Dorico).