I july 2014, Aircraftcabinmanagement.com wrote in their review of the A350 cabin design process:
...
Learning from its experience with the A380, where complex interiors caused delays, Airbus has introduced a cabin configuration catalogue from the start of the project as it plans to rapidly ramp up production. It should be noted that the participating companies are also risk-share partners in the programme, meaning it will be tough for new potential vendors to break into the market.
Apparently, it was well known that interiors can cause substantial delays. Still Zodiac Aerospace have been locked in as risk-share partner and can't easily be replaced. Apparently Airbus though sharing risk with Zodiac would mean reducing risk for delays. Apparently they were wrong.