Re: draft-config-exec conundrums...

As far as I confirmed, it seems that English document you cited and
Japanese one have almost the same information.

In default settings, Wanderlust calls wl-draft-config-exec via
wl-draft-send-hook just before sending.  If you want to edit a draft
after wl-draft-config-exec (for the case that wl-draft-config-exec's
result is not always correct), it should be called much earlier.  For
example, adding wl-draft-config-exec into wl-mail-setup-hook does the
trick.  Because wl-mail-setup-hook is not called when re-editing, you
need to add wl-draft-config-exec into wl-draft-reedit-hook if you want
to call wl-draft-config-exec also when reediting (for the case that
you want to edit a received message).

wl-draft-config-exec is intended to modify a draft only once even when
called multiple times (except when called interactively), but saving
and reediting will lose the information about whether
wl-draft-config-exec has already been done.  So, please be aware that
wl-draft-config-exec may be called and modify buffer multiple times
when you add wl-draft-config-exec into wl-draft-reedit-hook.

-- 
Kazuhiro Ito