Macbook Pro Storage Full Due to System

Check the preferences of your Adobe CS programs and see where the cache files are going. I don't think they are invisible but i could be wrong. As I said, Spotlight often isn't accurate about the kind of files so you may want to try rebuilding the index to see what is really going on. See this article: How to rebuild the Spotlight index on your Mac - Apple Support

The claim made by Spotlight that the drive is full of System files probably isn't correct even though it is correct that your drive is almost full. But just in case System files are taking over the drive, restart in Safe Mode (restart and hold the shift key until you see the Apple icon). Restarting in Safe Mode will check the drive directory, delete and trim cache files, and perform other tasks. Once it is complete restart normally and take another look at storage.

Because Safe Mode does delete some cache files, you'll see that there's more space free than before but as cache files are recreated that space will disappear quickly. The only reason this wouldn't be true is if for some reason your computer had a large number of orphan caches or logs which does sometimes happen. So if after a short time of normal usage you are back to about 5GB of free space it will be time for you to look for files to move to an external drive. Media files (video and music) are good candidates because they are large. Documents (word processing and the like) aren't good candidates because they are relatively small.