I know this is nearly 2 weeks old, but I only played through Benson's bad end 3 times before the word clicked for me. I thought you did a fantastic job of making it clear what the key word was while making the players work for it at the same time.
The people who miss it repeatedly have probably failed to pay close enough attention to the dialogue. That was my issue at first, until finally I was like "Okay, what is everyone saying" and paid super close attention.
It was a 'Eureka' moment for sure. Makes me feel like a detective which is awesome.