Though we use internally "fingerprints" of S/MIME certificates, those are nothing you can reliably identify a certificate with. They are defined by issuer and serial number.

Therefore we should identify them in the messages to the user with these.
Especially if the certificate is not available as at that point no "fingerprint" can be calculated.
And without Issues and S/N the certificate can not be searched for.

This information can be seen with --debug x509:

gpgsm --debug x509 --verify <signed-message>