It simple thing than complicated blueprint.
Menu -> buttons
Button -> event action
Button.click -> execute event action
Button.mouseover -> select the button as current button
Key press [e] -> curent button.event action.
This run ok and tested.
The concept , each button has an event action , when click it execute it.
The issue is execute button event action from keyboard.
You can name button by assign an id with it. When the mouse is over or use direct key to change the id then execute it as curent.