Spec comments:
 - The spec says to link to a .desktop file for the application.
This is typically installed with the application (or it is in KDE apps
anyway), I'm confused as to how this is intended to work.

- I would include project icon and project license in the file format.
Maybe this is linked to the above comment?

- I would allow for icon to be a remote path. An icon set like Oxygen
won't have icons for every single app that we'd want to show in a
store and I think it would be wrong to do so.

 - There's some attributes used in the example are not documented.
ie. width + height on the screenshot (which seems pointless anyway
when you're explicitly setting an aspect ratio in the spec)
the url element in the example has type="homepage" which is not documented.

- You've documented how the XML fits in with Gnome's i18n tools, which
I don't think is the right approach in a freedesktop.org page. That
should list the final intended output (file names/format), the gnome
page should list how to use the gnome i18n.

Regards

David