Hi
In the file solarized-css/test/org-hacks.org you have published has some neat functions and tips.
I noticed that https://thomasf.github.io/solarized-css/test/org-hacks.html#sec-1-7 has some functions to preserves the logic of level groupings and tags when archiving.
The line (with-current-buffer (find-file-noselect (org-extract-archive-file)) now has an error helm-M-x: Symbol’s function definition is void: org-extract-archive-file.
org-extract-archive-file and org-get-local-archive-location have been removed from org-archive.el. org-archive--compute-location has to be used instead.
Here is an example of how someone else applied the changes. daviderestivo/galactic-emacs@cb439c9
I am a org mode novice and I found the tips in you document very informative.