Yes, you can get a good replacement file from either another known good computer running the same version of Windows, the original installation media (if it is that version of file that is missing) or whichever Windows update had installed the file on the system in the first place.
At that point you would need to use the command line tools takeown and icacls or the Windows file properties GUI to take ownership and grant write permissions for the files, then return them once the replacement is performed.
SFCFix automates the process of taking permissions and ownership for the files, replacing them, and returning the permissions to the previous state among other things. As you suspected, there is a lot that could go wrong if SFCFix was used incorrectly.
It is a very powerful tool that requires training to use properly, so instructions are not provided to the general public at this time.
Sysnative does have a Windows Update Academy if you would be interested in learning the process of sourcing replacement files and how to use tools (including SFCFix) to make your own fixes :)
