Wes Hardaker's generic exported in contrib/lisp needs a small changed to make it compatible with the :for-backend generic parameter introduced in commit ed6d6760268a18ff5c49f4d98b433f6cf9500e1e.
@@ -620,7 +620,7 @@ underlined headlines. The default is 3."
(lines (org-split-string
(org-export-preprocess-string
region
- :for-ascii t
+ :for-backend 'ascii
:skip-before-1st-heading
(plist-get opt-plist :skip-before-1st-heading)
:drawers (plist-get export-plist :drawers-export)