[0] https://www.adn.com/alaska-news/aviation/2023/02/20/after-al...
The bug you cite, which you would not likely even know about if not for other commenters, was only caught because people asked for an old school manual calculation. Had the software process been more transparent it perhaps could have been caught earlier.
The fact that someone failed to properly implement the calculation in software does not change the efficacy of doing the calculation manually. Furthermore, the fact that there were people capable of eyeballing the accuracy of the software outputs seems to back up my point that there are tons of people capable of doing these calculations kicking around.
This is not rocket surgery. This is something that literally every private pilot with a Cessna does when they encounter a novel loading. Stop making it out to be some super scary thing requiring serious expertise to not screw up.