Invalid id for Appstream metadata
The .desktop
file name for gbrainy needs to be present in its Appstream metadata.
For an example of how this is done, see evince.
If you end up changing your id, please add a provides field.
It looks like you can either use the same id as your .desktop filename or use a separate launchable
field.
Until this issue is fixed, Debian and Ubuntu won't use the Appstream metadata. The gbrainy listing in GNOME Software currently uses a minimal listing based on the Debian package description.