Don’t worry, I’m a math nerd too. And thank you for answering my inquiries.
Edit: Comment: I don’t think them being 1000 pounds is too much of a problem as that’s about the average weight of a horse, so, as seen with Catti, them being able to run is not implausible. Additionally, there is a genetic mutation in real life, which causes the body to stop producing a protein called myostatin a muscle growth regulator, causing myostatin-related muscle hypertrophy. Search up “double muscled cows” to see what I mean. Even gene therapy to purposely cause this mutation is available today. (They’re literal muscle mommies)
Edit2: An addition to my previous comment: You may know that our brains won’t allow our muscles to use their full strength, because if it did, us tearing ourselves apart would be a real risk. The average person has their limit between 10 and 15% of their true strength, while a professional boxer has trained this limit up to 35% of their full strength, or in the case of high stress situations there have been stories of “hysterical strength” where the body simply ignores these limits. Due to these characters being manufactured/possessed it is entirely possible that their muscular limit is coded to be far higher.
Edit3: Final note: This is assuming that their biology is even human adjacent. It is entirely possible that they could be using something more efficient which may be found in other animals like elephant muscles for their ability to bear and lift heavy loads, the pistol shrimp and mantis shrimp for strike strength, saltwater crocodile for bite force, electric eel for electricity like you were talking about before, ability to hibernate to conserve energy, the ability to draw energy/resources in unconventional ways or from unconventional sources, simply using the same amount of resources more efficiently, etc. Although we’ve been championing AI and machines, biology still is far more efficient/superior in nearly every way.