They are in.
The actual way to have them work is to actually go in the Project bar, right-click the "Files" folder and then select the type of file/data structure you want to edit in the "New" folder.
This will result in opening the appropriate editor (array, dictionary or text for most other kind of format).
You will have to close the tab in order for any modification to be taken into account into the file.
Then if you want your file to be read in an array, you add the AJAX plugin and treat the file as a Project File.
On start of the first layout of your project, or where you want it, you acquire the file and then use the Load action within the appropriate data structure to load AJAX.LastData.
+ System: On start of layout
-> AJAX: Request New Array.json (tag "Array")
+ AJAX: On "Array" completed
-> Array: Load from JSON string AJAX.?LastData