That’s the wrong folder. That’s where the plane itself is stored. The files you are looking for are elsewhere in your user profile.
“C:\Users%USERNAME%\AppData\Local\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalCache\SimObjects\Airplanes\”
You should see a folder per plane. Inside will be a “state.cfg”, and if you have created custom camera views, then a “cameras.cfg”. That is where you need to copy your friends “cameras.cfg”.
From what you have said though I suspect you have overwritten the planes default “cameras.cfg”, possibly with the custom one so it’s probably broken at this point.
When you use the key sequence to create a custom camera view based on what your current view is, it gets written into the planes sub-folder, inside that folder I listed above. That file only has what custom camera views you have created.
It is not the same as the “cameras.cfg” that a plane comes with, which has way more configuration inside it, with different views such as “Pilot”, “Instruments” etc.