It is a personal choice to decide if you should pay the Mexican moving violation or fight it.

The current Drivers License Compact (DLC) does not include Mexico but the Drivers License Agreement (DLA) which is supposed to take over for the DLC, once it is finalized and accepted by State's legislature, will include both Canada and Mexico.

You should contact the California Department of Motor Vehicles (DMV) to find out if the moving violation which you were charged with in Mexico will be reported to them and if it will be placed on your driving record.