@ewitsbrooke
The problems you're having sound completely Mod related. Creating the symlink to store the Sims 4 folder externally has absolutely nothing to do with game performance and improving gameplay. It simply frees up space on the internal drive.
> changed iCloud settings so the Symlink is now on the desktop instead of iCloud documents (EA folder is still on the external).
The symlinked folder is on the desktop? The game won't launch any data from a folder on the desktop.
Can you post a screenshot of your Documents folder contents. Scrub out any personal info.