The flatpak provides yet another validator tool which provides valuable information. I have adjusted changelog first letters to upper case according to its output.
flatpak run --command=flatpak-builder-lint org.flatpak.Builder appstream harbour-amazfish-ui.appdata.xml
As is mentioned in https://github.com/flathub/flathub/pull/5173 the appdata.xml should be part of main repository.
The gnome-software listing and flathub listing (which I am not able to preview) is build from that file
There is Changelog section which should be updated with new release.
It is possible to validate file using following command
The flatpak provides yet another validator tool which provides valuable information. I have adjusted changelog first letters to upper case according to its output.