I too am in the food industry- have been all my working life. I have no idea about the mango on your cruise, but we sailed Nova for 16 nights Nov/Dec and this definitely was not the case. All the fruit was amazing quality. In fact, all the food in the restaurants was first class.
It was only our second Silversea cruise and we’re unable to compare with the other equivalent cruise lines, but we are extremely happy with everything. I really don’t understand how much luxury people want/expect. We’re booked on 3 more Silversea cruises - and are really looking forward to sailing the Moon and the brand new Ray.