It is possible that the rar collection already had the CRC error before the SFV was done.
It's also possible that if your computer is doing a lot other work it might mess with the extraction process. You may want to boot into safemode and try to extract the files again. Or copy the original files again.
You may also want to check your event log in the Computer Management (under administrator tools). If the failed extraction is a result of the computer messing up it will appear in there with a yellow symbol.
Also try Recovery Toolbox for RAR
designed to recover information from corrupted archives of the RAR format. You can use it to completely avoid or at least minimize losses of compressed data.
For more: https://rar.recoverytoolbox.com/