The linked article stated that the trials began on 12 August.

It is true that the new systems caused delays to the programme.

However, reverting to the long-out-of-production systems of the Nimitz class would require a significant redesign of the Ford-class ships and cause further delays.

The Ford class is designed around an electric system. Replacing them would require not only a redesign around this system, but also of the entire energy system and distribution, e.g. the transfer of steam to the catapults. Perhaps 50% of the ship would need to be redesigned, and new production lines would need to be set up for outdated technology.