How to check Raw Files in my iCloud Drive?
The only way I know of to achieve this is by creating a symbolic link to your iCloud Drive folder. Open a Terminal window and enter the following:

ln -s ~/Library/Mobile\ Documents ~/Desktop/iCloud\ Drive

This will place a symbolic link to your iCloud Drive on your desktop. You may move it wherever you please.

Starting with El Capitan, trying to navigate to that folder using the  Cmd  ⌘Shift ⇧G shortcut takes you instead to ~/Library/Mobile Documents/com~apple~CloudDocs. Incidentally, that is the same location that the Favorites shortcut points to.

Do note that opening most of these folders will take you to ~/Library/Mobile Documents/com~apple~CloudDocs. However, you can expand them to inspect their contents in List View.

This comes in handy when troubleshooting certain iCloud synchronization issues, such as (in my case), Text Replacements not making it to my Mac.