If the subkey for an ADSK set by default-new-key-adsk is not in the keyring, the key generation error in Kleopatra is generic:

If possible, the error should include, that it's about a missing ADSK to point the user in the right direction.

I once forgot to delete the gpg.conf entry and it took a while until i figured it out.
As soon as ADSK is used more widely, many end users with admin provided setups might be confronted with this.