There is nothing to stop you - on the contrary, it would seem to make sense - to make a public statement that a complaint was made, investigated in accordance with due practice, that a finding was arrived at and that all interested parties have been informed of the outcome.
MO code of conduct findings are published. They include the name of the complainant, the subject and any witnesses, a summary of the findings and the conclusion. Just because it contains a name does not mean it is excluded from being published.
It sounds like your clerk wants their cake (to see the other party’s letter) and eat it (not show their own.
Sounds like your clerk needs some DPA training or simply told to wind their neck in. They can’t expect to have their own letter held in confidentiality whilst demanding to see the other….