Sushi’s stats converted from Metric (with BG having stated there may be a slight error in the conversion to Metric): 4' 11" & 70 lbs
The Lockheed-Martin employee used as a basis for Sushi’s h/w:
4' 9" & 82 lbs
In T20 Str 12 is slightly above average for a human (+1 modifier) and Con 10 is average for a human (no modifier).
So most female Olympic Gymnasts don't actually exist then? Circus Midgets and Dwarfs can't lift wrenches let alone say dumbbells? Shannon Miller was only 4'10", 79 pounds in 1993 and had already won five Olympic medals. I’d say she’d be more than capable of lifting a wrench and would have stats well above Str 12 and Con 10. So Str 12 and Con 10 are quite possible for someone of such a build.
Also keep in mind by level 8 there have been two ability increases for a T20 character and there is no direct correlation between height/weight and abilities in either CT or T20 nor are there distinctions between the sexes in abilities. For that matter, as has already been pointed out, this character was not originally created in T20 chargen nor is fresh out of prior history with no adventuring.
/me shrugs
Frankly this is Science Fiction Adventure in the Far Future not Realistic Adventures in Medical Science.

Keeping that in mind even for modern day that’s well within the realm of possibility let along taking into account environmental factors, ancestry, nutritional levels and what not and using a setting like the OTU.
I will note you seem to have had no such problem with the similar h/w Assistant Engineering Goddess & also ex-circus acrobat Asu
(T20 stats) (her height fluctuated and may actually be closer to 4’10” but the point still stands). She has since that post in the course of about a year or two of gametime increased her Con to 8 (-1 modifier) and still maintains a chronic diet of Insta-noodles and Insta-natto coupled with a regimen of overworking, staying up too late, and not getting enough rest, thus an average Str & slightly lower than average Con. She also was originally created in
(CT stats). There is also Endeavor’s roving ace reporter Siofra who is 4’1” with higher Str and Con (also Belter-born) and is based on an acquaintance of Siofra's player.
As for the Lockheed-Martin employee, it was stated she was used as a model for size and stature and that someone of such shape could lift a wrench and could accomplish such skills. Said employee I am assuming was not a prodigy. Sushi is a prodigy, born in space (belter) in the Far Future and has lived most of her life in low and zero-g environments, most of the time doing physical labor of some sort. Having been exposed to jump-space at a young age she has an unusual gift for working with it. Honestly I am wondering if you read more than just the T20 stats.
As always, YMMV.
ph34r the short cute ones
Casey