The only memorable collaboration I remember was Cathay and Mandarin Oriental back in 2014/2015 when they had the First class catering with various top chefs from different MO hotels on routes such as LHR, CDG, JFK, HND, etc. The dishes were premium quality and unique from what I recalled.
The current Duddell's and Louise collaboration got so repetitive/unappealing, it was the same few dishes being offered for months now. For almost a year, the same Pre-order "Cathay Signature" dishes were being offered to both First and Business class pax with no differentiation between First and Business as if they just gave up on their First catering completely.
I agreed with the other poster, I much prefer a simpler dish done right than the many of these fancy collaboration that looked good on paper but turned out meh in the air.