I'm trying to organise my 11GB's downloads folder (don't judge me!) and want to rename my cc so that it is, well, more organised.

I know I can rename filenames but am not sure if I can do so if the content has been used in the game already.

Yes, you can rename them, but if they have a note from the creator, such as Pescado and TwoJeff's mods must be put in a specific order, or a global needs to be placed before another mod, I wouldn't rename those.

I'd take a backup just in case something goes wrong.

The game goes off the internal GUIDs not the filenames. As kankritty indicates, it's only when load order is an issue that you need to worry.

Thank you Kankritty and Maxon. I'm making a backup as we speak. I've read in the help section that you shouldn't change mod names but just wasn't sure about regular cc. Now to begin the arduous process of going through the tons of cc I've accumulated throughout the years. Thanks again!

And while you're renaming, remeber not to use other characters than Aa-Zz, 0-9, - and _

Other characters can slow down game performance or mess with the file. That goes for spaces, punctuation, commas, and special characters like ()[]$£@"#%&/,.;:*^~¨ and so forth. Some of these you won't be able to use, as they can't be use in filenames at all. Others can be used, but the program will spend extra time reading them, or perhaps even skip them because they can't be read.

Also, if you use . in the filename, you can lead the file to think that anything behind the . is a file extension, so if the file is originally named "blahdiblah111.package" and you name it "painting.11.of.a.bird.package" you might be in for some troubles.

All in all,
~[creator]~painting of a bird.11&12(a)^o^ mesh.package
or any similar variants would be a very bad filename.

But soemthing like this
Creatorname_PaintingOldFrame_MESH.package
Creatorname_PaintingOldFrame_REC-Parrot2.package
would be better filenames.

Using the creator name, a descriptive title, color/pattern/similar, and telling yourself or others that it's a mesh or recolor is very helpful because it's descriptive so you can relocate them, and it helps sorting the files. If you have two recolors of the same item named "blue.package" and "red.package" they'll not be anywhere near each other when you sort after name.

Also don't fall for the temptation to name something simply
blue1.package
haircurly-blond.package
chair-flowery-211.package
Because you'll never ever relocate them...

Thank you for your advice Simmer22! I will definitely refer back to your post once I start the renaming process.