Hi @vince_faller ,
I found this community solution to be helpful and I think it'll do the trick for you, at least in part.
Apparently, once the JSL file is open, you can have a line that says Convert File Path(""); and it will show you the current directory. But, I think you need to run it from within the JSL script file. It appears that if you run it from another script window, then it returns the JMP file path.
Hope this helps!,
DS