iTunes - How to actually synchronize libraries between 2 Mac with Google Drive
I find Hazel to be a very useful app for this and many other tasks. It works similarly to Folder Actions, only it has more flexibility and actions, uses less resource, and it actually works. On Mac1, I assigned the Sync action to each of the iTunes folders I want to keep in sync. (I advise against syncing the Applications folder. It requires user interaction.) It only syncs one direction, so it won't start deleting or duplicating items on Mac1.
On Mac2, I assigned the Import into iTunes action to the parent iTunes folder, naming a generic playlist. It detects any new files added to any of the subfolders and adds them to the library.
The only thing is that it will also delete files if you delete them from Mac1, and it doesn't delete them from the library in Mac2. I have a scheduled job for Track Sift to run routinely, anyway, and it cleans up dead tracks, amongst other housekeeping chores.