Hi Jakub,
Some questions I have after trying to fix the items you discovered:
1. I'm packaging and testing in wheezy, do I have to be using sid? lintian4python appears to be only in experimental.
2. Should I upgrade packaging to standards version 3.9.4 or can I keep at 3.9.3 while I iron out the current packaging issues?
3. I have addressed the other concerns you have about d/*. I have yet to test the fixes you provided for upstream and submit them, however, should I patch myself for current package or wait until they are incorporated upstream?
Thanks,
Robinson