Boeing customer option on the 777 is to remove Gross weight entry from LSK1. Not sure if AF purchased this option on the 77F fleet (2 aircraft).
MTOW on their 77Fs is 347,000kgs (Highest option on the -200LRF).
Operating CDG-MEX fuel would be 90-95T. With a payload of 80-100T TOW would be 320t up to MTOW. If indeed they were off by 100t they either entered the wrong TOW or ZFW in the TOW field (if that is enabled on their aircraft). EK almost lost a A345 at YMML a while back due to the same mistake. Gross Weight being entered 100t lower and the crosscheck wasnt done correctly.
Since then, they have purchased the the Gross Weight try field REMOVED option on the 777 fleet and I assume the Airbus too if that is an option. And also disabled it on previously delivered B777s. This being one step along with additional training and emphasizing of doing the weight & balance calculations separately and crosschecking.
At least the AF crew realized acceleration was insufficient and aborted before going off the end...However you do wonder if they were experienced on type why they would let themselves get away with a far too big de-rate/assumed temp. If you are running the takeoff performance numbers for a 11h+ sector, and the assumed temp comes back as TO-65C that should raise a red flag....