I am seeking this support because when adding Attachments to Org File without Headlines, I get a user-error: Before first headline at position 1 in buffer filename.org, even if the attachment has been successfully added. I hope there are no errors, and the #+FILETAGS of filename.org buffer has added `org-attach-auto-tag'. After a simple exploration, I found that this requires the support of org-set/toggle-tag to modify FILETAGS.
Emacs : GNU Emacs 30.0.50 (build 1, aarch64-apple-darwin22.4.0, NS appkit-2299.50 Version 13.3.1 (a) (Build 22E772610a)) of 2023-05-25 Package: Org mode version 9.6.6 (release_9.6.6 @ /opt/homebrew/Cellar/emacs-head@30/30.0.50_1/share/emacs/30.0.50/lisp/org/) -- Tianshu Wang