Doom Emacs - `custom-theme-set-faces` not working for `org-level-n` faces

Question

I am trying to modify a few faces for a specific doom-theme in Doom Emacs.

I am only interested in an emacs-lisp solution, I do not want to customize via the dedicated Emacs interface.

I got the basis for my approach from this thread. I managed to get it working as intended for org-tag face, but org-level-n attempts have no effect whatsoever.

Usually in Doom Emacs, it is a matter of loading sequence when customization has no effect and the solution comes from identifying the correct hook/mode/package after which executing your code.

But what gets me stuck is that both faces I am trying to change are defined in the same module (org-faces.el if I remember correctly). So I am out of ideas as how to investigate further.

This is what I am using in my config.el:

(defun customize-doom-dark+ ()
"Customize doom-dark+ theme"
(if (member 'doom-dark+ custom-enabled-themes)
    (custom-theme-set-faces
     'doom-dark+
     ;; Attempt using complete property setting 
     '(org-level-3 ((t (:foreground "#66b4e3"
                        :weight bold))))
     ;; The ':inherit' approach I would rather use
     '(org-level-4 ((t (:inherit outline-5))))
     '(org-level-5 ((t (:inherit outline-6))))
     '(org-level-6 ((t (:inherit outline-7))))
     '(org-level-7 ((t (:inherit outline-1
                        :weight normal))))
     '(org-level-8 ((t (:inherit outline-2
                        :weight normal))))
     ;; I also tried setting 'org-tag' with ':inherit org-footnote'
     ;; It works as intended
     '(org-tag ((t (:foreground "#D9DAA2"
                    :weight normal))))
     )))
(add-hook 'doom-load-theme-hook 'customize-doom-dark+)

Answer 1

I finally found the solution on doom emacs discourse, I was going for an overly complicated approach, but I still cannot find the solution in the documentation, so this might be useful to someone until the doc gets updated.

(custom-theme-set-faces! 'doom-dark+
  '(org-level-3 :inherit outline-4)
  '(org-level-4 :inherit outline-5)
  '(org-level-5 :inherit outline-6)
  '(org-level-6 :inherit outline-7)
  '(org-level-7 :inherit outline-1 :weight normal)
  '(org-level-8 :inherit outline-2 :weight normal)
  '(org-tag :foreground "#D9DAA2" :weight normal))