Re: Accidentally moved my Electronic Arts folder to desktop.
@AgnewLeah Sims 4 will only read the contents of one user folder, and you can always find out which one that is through this in-game method:
https://sims4.crinrict.com/eng/2018/07/how-to-find-your-user-folder/
Since the game is almost certainly not reading the Sims 4 folder on your desktop, that folder's contents are doing nothing, and deleting the folder would have no effect on the way the game runs.
Definitely move over the contents of Tray though. These files are the data for anything you've saved to your in-game library, whether your own creations or those you've downloaded from the Gallery. It's not your Gallery uploads per se, although you've probably saved all your Gallery uploads locally as well. Point is, put those files back and your in-game Library content will be back too.
I don't know why Microsoft support would tell you not to add the files back, unless it's a "leave well-enough alone" kind of reaction. But if your creations and downloads are important to you, you'll need the contents of that folder.
If you'd like help sorting out the OneDrive mess, just ask. In that case, please also list the full file path to your user folder as you see it in-game, like the link above describes.