I'm surprised you had this on Panorama deck. Much more of a concern for Dick Williams who posted he'll be on Continental. This vibration is common especially on older ships (Galaxy built 1996) and toward the rear where engines and props transfer it. Normally it's heaviest at the rear of the lower decks. The only time it's normally as bad as you describe is coming into and leaving ports.
Sorry to hear about your unpleasant experience. Don't expect too much sympathy from Celeb Cust Serv. The cruise lines take much better care of passengers onboard the ship than they do after the sailing. It's not Celeb specifically, actually they do a better job than most with issues. But in the case of the industry response to complaints, even valid ones better means pretty poor instead of horrible.
Thanks for the heads up on this, will advise future clients to strongly consider forward if booking Galaxy.