This calls for a good logging system.
Something that stores any action you take on a .org file (editing an
entry, marking it as DONE, clocking it, refiling it, etc.) and that you
can easily *query*.
For now the logs are somewhat hackish, more a casual convenience,
and the actual system is not good for stable parsing.
That's something I considered working on at some point, but starting
this before org-element.el was complete was not a good idea.
Ok, now org-element.el is complete...  :)