Peter Fischer reports by mail the currently generated files aren't valid:

I just yesterday found out that there exists a tool to check desktop
files against an "official" rule set: "desktop-file-validate", part of
https://www.freedesktop.org/wiki/Software/desktop-file-utils/

This tool complained about the files generated by your Generator:

desktop-file-validate /home/peter/.local/share/applications/DRAKON.desktop
/home/peter/.local/share/applications/DRAKON.desktop:
warning: key "Encoding" in group "Desktop Entry" is
deprecated /home/peter/.local/share/applications/DRAKON.desktop:
error: value "False" for boolean key "Terminal" in group "Desktop
Entry" contains invalid characters, boolean values must be "false" or
"true"

The lines which complained about are present in the normal default
boilerplate of your generator. I think the reason ist
copy&paste&derive, like often times in the opensource world (I've done
this, too ;) ).

If you could incorporate "desktop-file-validate" into GNOME .desktop
file generator anybody could write standards-compliant desktop files.

That said, thank you very much for having written GNOME .desktop file
generator! :)