It really does happen......but you won't see it very often.
We've traveled all over the Caribbean, down as far as Bonaire & Curacao. We watch for it every night...(it's become a bit of a joke among our group)
But....we finally did actually see "The Green Flash" on our trip to Bonaire last November. It was very cool to see....but if you had blinked at the right moment, you would have missed it.
It's possible that you could see it on the Western. If you have enough open ocean, with no other islands in the way...and a clear night sky.
It's fun to just sit and relax and wait, even if you don't see it!