There is one improvement I can think of for FPI Maker off of the top of my head.
While the app does check for syntax it doesn't actually check to see if the script works.
If FPI Maker had some kind of built in script checker that would be cool.
Also of note is that not all of the commands found in the FPSC manual are actually present in the FPSC engine.
Your best bet might be too e-mail Lee and have him send you a list of current commands for FPSC.
Some commands have been added since V1 as well and Lee would be best qualified to give you the current list.