Thank you!! I'm very happy you liked it!
Bookend is a type of skill, it says that you need to play it first or last in a routine, then the effects will trigger.
The +2 effect in your case is probably from the Wave card? It says "+2 Glory if played first or last in a Routine"
It's kind of like a real bookend that keeps the books on a shelf from falling over, bookends are placed on the very left and right on a shelf.
I hope I explained it well :D