As per Peter -
Installing Scripts instructions here
https://creativepro.com/how-to-install-scripts-in-indesign/
You can find a way to quickly get to your scripts - then copy them to your CC folders or backup anywhere - I back my up on Dropbox for ease of access anywhere in the world.
I could back them up in CC too, but I just haven't done that.
GREPs can be found on your computer
username/Library/Preferences/Adobe InDesign/Version 6.0/en_GB/Find-Change Queries/
Thread here with further info
https://community.adobe.com/t5/indesign-discussions/saved-grep-queries-where-do-they-live/td-p/2321271
You can back them up.
It's a good idea if InDesign / Creative Cloud offered the option to back up these up somehow.
You can put a feature request here
https://indesign.uservoice.com/