There are still some icons from the fallback Gnome theme in Evolution that could easily be replaced by the breeze theme counterparts, like the app icon itself, 'send / receive', 'inbox', 'trash' (folder icon used), 'archive', 'tasks', 'memos', 'drafts' and maybe some more I might have missed. As Evolution is quite a popular application, not only for Gnome users so I think this should be fixed. Thanks! Using Frameworks 5.36 right now. Has this been fixed since then?
I checked and you're right, even as of KF 5.41. There are definitely Breeze icons for all of these, but probably Evolution uses nonstandard names to refer to them. Please report this to them.