I’m a newcomer, so please take it with a grain of salt, but “source code” is basically just an arbitrary, human-readable representation of the actual program that the compiler is supposed to generate. So in your case a file (or set of files) that contains all your scripts and can be opened in the free version of Multimedia Fusion 2 is your “source code”, even if the file is binary and not text. The point is that someone can use that file (or files) to read your scripts, modify them, and/or reuse them.

Source doesn’t literally mean code. I believe project file is good enough if your software doesn’t encrypt or obfuscates the contents.

There are several environments where the “source” is more configuration and less code (Unity, Gamemaker, Stencyl). Just zip up your project folder, whatever is needed for someone to build your game, and that should suffice.