Hey there!
This code is designed so that the final file can be obtained only through the "save" function. In connection with this line, you will not be able to use the temporary file.
By the way, the same function is used in GameMaker: if you use the free version of the program, the saved (final) file has, among other things, a watermark. When you are making the game, you can test it (similar to the "RUN" button in my program), there is no watermark in it. But if this file is being run, it should be generated and saved somewhere, right? True. But the problem is that the file runs only in first 10 minutes after the generation. Here you can learn a little more about this here: https://www.youtube.com/watch?v=UIMALxZLyeg
And yeah, about the bug: So far I do not understand what the problem is. Can you send me the generated file - "script.bat" (or only a code from the file - even better)?