They have to do complex CG and weight distribution calculations

Eh, I'm an airline pilot and while I am required to have the knowledge to do this manually, it's done by computer nearly 100% of the time.

Also, modern transport category aircraft have a pretty wide CG envelope that allows for a large margin for error and sloppy calculations. Every adult that we calculate has a standardized weight of 190lbs and every standard checked bag weighs 30lbs. Is this accurate for every person and bag?

I appreciate the respect you give the job and you're right that in the moment, the captain's word is final but you better believe there will be consequences for the wrong decision.

I'd have to double check our books but I'm fairly certain that large containers or instruments in the cabin are fine under the provision that they are found the be adequately secured by the seatbelt. Could a cello go rogue under turbulence and hurt somebody? Sure. Would I go to jail because of it? Absolutely not.