"Отображаемое имя в сообщениях" должно применяться и к цитатам

[Moin]

I think this was completed here

Display full name not username when attributing quote or reply

I have added the pieces necessary to prioritize full names when: prioritize_username_in_ux = false display_name_on_posts = true for the cases described in the OP. Thanks for @JonathanShaw for pointing this out