Is the function bst_process from the script not calling the same process as the Brainstorm interface?
It depends for what.
If you want some help from us, please try to be more specific.
If you're already at a level of editing the inverse functions, you are probably beyond the scope of this user forum.
You would probably much more efficient by learning how to use the Matlab debugger: click on the line number to set up a breakpoint at the beginning of the function you edited, run the computation either from the interface or from a script, then when the debugger stops the execution, you can start inspecting the contents of the variables, and execute the code line by line to see where the execution goes and why.
This would be the most direct way for you to understand why your files are not created.
If this does not feel intuitive to you, start by watching a tutorial introducing the Matlab debugger.