Hi Jack,
On the Mac we have a problem: OS X doesn't make it easy to access the contents of an application bundle. In other words, you cannot select a folder inside the PixInsight.app application. This means that the Script > Feature Scripts menu option is mostly useless to regenerate the list of standard scripts.
I still have to think on a good way to overcome this problem. Probably the best way is a new console command, but I haven't implemented it yest. I'll think on this for version 1.5.3.
Right now you have two options:
- Reset the entire PixInsight configuration. Right-click the PixInsight.app file. Press the Ctrl key and hold it pressed. Select the Open option. In this way the PixInsight application runs in Uninstall mode.
Warning: You'll lose all your personal settings and PI will forget all recently opened files and folders.
- Use the terminal. Don't panic:
it is very easy and works flawlessly. Assuming that you have PixInsight.app on your /Applications folder:
* Open the Terminal application (you have it on /Applications)
* Type this command and press Enter:
cd /Applications/PixInsight.app/Contents/MacOS
* Do the same with this command:
./PixInsight --default-scripts
Now PixInsight opens and all of your scripts are there automagically

Exit PixInsight and then close the Terminal. That's all! OS X is UNIX. That's why it's so powerful!