Hi! One more thing that I just noticed: The desktop-entry file in the package isn't installed into /usr/share/applications, which means the software doesn't show up in menus. Can you please fix that? If it's an extra maintenance burden, you might also just want to drop the menu entry files and ship only a .desktop file, the menu is rarely used nowadays while everything relies on .desktop files :-) You should be able to drop the ".files" files in debian/ and add the content properly to the respective .install files (which can copy stuff from debian/ to the correct destination). That would be easiest, of course, d/rules can also do the same in a less declarative way.
Cheers, Matthias