A simple answer is yes.. that should be possible.
I am trying to revert my MacBook Pro back to a backup of High Sierra that I made on version 10.13.2
So this backup has not been touched since it was made.. no incremental backups over the top of it?
If that is the case this backup can be used to completely restore the computer to how it was at the date of the backup.
have made subsequent backups including these files via Time Machine.
These subsequent backups were made to a different location to the 10.13.2 one?
If so then recovering just the libraries should be no problem.. but why don't you plan for the worst.
Get a USB drive of suitable size and make a bootable clone of your computer. Then you have a simple way to access your current libraries. I would also do a backup of just the libraries.. since these are easy to do..
Then you can revert your computer.. using setup assistant from the recovery boot partition. And once that is working update your libraries.
I am perhaps more concerned at the premise that the computer works poorly on a more recent revision. If you upgraded the OS from 10.12 to 10.13 and had issues.. that would make sense.. but versions are mostly for patching bugs and security. I would be more tempted to do a clean install of the latest OS. Then use migration assistant to recover your files.. which would include your current libraries. If the computer is still behaving poorly it is more likely to be an actual hardware fault.
