I've figured out the issue with the northern staff-bow. That's the good news. The bad news is I don't think it's fixable.
In the original incarnation of the recipe the item used "Northern Spear" as its base item (which gave it the ability to ski), and then changed the skill to BOW in order to make it function as a bow. This worked fine. UNTIL, the game was updated with the bow-string update, and then it stopped functioning as a bow, and could not have a string applied to it because the base item was not a bow.
So, the base item was changed to "Northern Bow" (by me) to fix the bow problem. But in doing so, it stopped functioning as a ski-item (since it no longer inherited those properties from the Northern Spear).
Unfortunately, based on my current understanding of modding, this means it is not possible to make an item that functions as both a bow and a ski-stick.
The best "solution" from my present stance is to remove the item from the menu entirely, since it serves no real purpose in its present form.