No - you can't. Or you can, but then you'll get one big STG file out of it, not one output file for every input file.
Try my script at https://github.com/TheFGFSEagle/fgtools ... dit-stg.py instead - just give it your Objects/ directory as input with -i / --input, and let it do the rest. You also need to give it the location of your scenery / multiple paths separated by your OS's pathsep (: on Linux, I always give it first my custom scenery, then TerraSync) with -s / --fgscenery, and the path to your FGDATA folder with -d / --fgdata. Additionally, if your fgelev executable is not in a folder present in the PATH environment variable / or not named fgelev, give the script the name of / full path to fgelev with -e / --fgelev. I'm 90% sure it works, but there's a 10% chance it might throw some SyntaxError or something like that because I didn't use it in a while but changed a few things !