Wouldn't be the first time that something popped up in a Traveller book that can't be re-created using the design sequences.
http://www.travellerrpg.com/CotI/Discuss//showthread.php?p=116339
FYI: TL 12 ship with a TL 13 jump drive and power plant
There was also one of the design sequences in FF&S (I don't recall now which one off the top of my head) that simply couldn't produce equivalent 20th century real world designs. Simple solution was just go ahead and use what FF&S gave you with the knowledge it was "wrong" or use the contemporary numbers for whatever it was and not stress about it.
Ultimately though we're speculating here about the "how" behind a canon storyline. The story is indeed correct as you state by default. The "how" has more wiggle room.
http://www.travellerrpg.com/CotI/Discuss//showthread.php?p=116339
FYI: TL 12 ship with a TL 13 jump drive and power plant
There was also one of the design sequences in FF&S (I don't recall now which one off the top of my head) that simply couldn't produce equivalent 20th century real world designs. Simple solution was just go ahead and use what FF&S gave you with the knowledge it was "wrong" or use the contemporary numbers for whatever it was and not stress about it.
Ultimately though we're speculating here about the "how" behind a canon storyline. The story is indeed correct as you state by default. The "how" has more wiggle room.