So I started with this one because it was the easiest. To reduce message fatigue, I only display compliance information if gnupg is in co-de compliance mode.

Now "the document" does not specify what should happen if a message carries multiple signatures. What I currently do is:

1. One signature: Display compliance information.
2. If there is more than one signature, I state that
   1. all are compliant,
   2. or that some are compliant,
   3. or that none are compliant.

(kleopatra does not display individual signatures if there is more than one).

Disregard my comment above. I now display the compliance status for every signature and for the decryption process.