Thank-you for the report, Jeff.
This is an interesting one. Wikionary and every other online dictionary I
can access
consistently claim that the simple past and past participle are
"backcasted".
The full OED (at least my 20-year-old printed edition) does not list any
inflexions at all.
My electronic OED (as well as the NAOD) does indeed list "backcast", and I
am certainly
inclined to favour ANY Oxford Dictionary (even a rebellious colonial one
;-).
I have now applied the appropriate patch, and uploaded a new release.
Thanks again!
Damian