Body Skeleton Model Assistance

Hello community,

I'm a college student trying to work on a skeleton model for an assembly and this one part gets flipped and inverted, teacher just tells me its faster second time around and i know you should be able to fix it, just getting more mad trying to revert it. ( no I don't have a backup before it flipped)

Any ideas how to fix it, I'll link the files, picture of what it looks like and the tutorial, hopefully someone can figure out why its flipping that piece.

Thank you!