Re: What will happen if I delete my tray files?

All that you saved to your library is what is stored in the tray. I don´t think it will disappear from your current game, however, it will no longer be in your library and might be lost in case your game crashes and needs to be reinstalled. Of cours you could re-download from the gallery but if it is that much it is very likely that you won´t remember every single piece of it, I guess. Not sure if it is useful for you but you may try the little tool called "Sims 4 Tray Importer" - it allows you to have a look at the stuff you have stored in the tray folder. Link: https://luniversims.com/files/file/73-sims-4-tray-importer/

I have two more useful links for you.

1. A page that explaines the different types of user files

Link: https://sims4.crinrict.com/eng/2014/09/user-files-explained/

2. A page that explaines how to organize files in the tray AND lists all kind of file types that are used for households, lots, rooms etc.

Link: https://www.carls-sims-4-guide.com/forum/index.php?topic=26535.0

Might be useful for you. Have a look at it.