Syntax for Symbolic links in High Sierra

Yes. That is the concept exactly. Your large libraries lived on an external drive and you need to create new symlinks to point to them. (remember first to rename any existing libraries per the original posters workflow.)

Then create new symlinks that point to your content on your external volume and directory.

FOR EXAMPLE: I have about 80 GB of libraries for various heavy programs referenced with the following symlinks for IK Multimedia, Logic, Final Cut and Adobe apps.

In my setup, I created a "/Library" folder on my external drive is called "SFS Video"

NOTES: 1) The colon : is used for the backlash in front of library on volumes

2) Place a Forward Slash before a space in a directory name\

TERMINAL COMMANDS

sudo ln -s /Volumes/SFS\ Video/\:Library/Application\ Support/Logic /Library/Application\ Support/Logic

sudo ln -s /Volumes/SFS\ Video/\:Library/Application\ Support/GarageBand /Library/Application\ Support/GarageBand

sudo ln -s /Volumes/SFS\ Video/\:Library/Audio/Apple\ Loops /Library/Audio/Apple\ Loops

sudo ln -s /Volumes/SFS\ Video/\:Library/Audio/Impulse\ Responses /Library/Audio/Impulse\ Responses

sudo ln -s /Volumes/SFS\ Video/\:Library/Application\ Support/IK\ Multimedia /Library/Application\ Support/IK\ Multimedia

sudo ln -s /Volumes/SFS\ Video/\:Library/Application\ Support/Adobe /Library/Application\ Support/Adobe

sudo ln -s /Volumes/SFS\ Video/\:Library/Application\ Support/Avid /Library/Application\ Support/Avid

sudo ln -s /Volumes/SFS\ Video/\:Library/Application\ Support/Avid /Library/Application\ Support/Avid

sudo ln -s /Volumes/SFS\ Video/\:Library/Application\ Support/Final\ Cut\ Studio /Library/Application\ Support/Final\ Cut\ Studio

No Idea. But you can test your setup without risk. Just follow the steps in the original post (to copy over and rename folders) and then use the syntax I show here for the Terminal commands. If it works then you can delete the volumes on your local drive.