What this executables tag refers to and what would it be used for?
It seems that the value specify what language the module is implemented in, but that should not matter much - you can compile python code to be an exe file, you can also create executables by bash scripting, you can run .bat files on Windows…
Do you want to specify what software you need to use to launch it? Then the options should be system, python, bash, etc. and the tag name could be “launcher”, “interpreter” or something similar.