Another correction: Crossbow Stock uses Iron Bar, not Steel Bar
Wow, that's pretty weird and most likely a bug since that's one of the recipies physically printed on the cards of the kickstarter backer edition...
Please fix this, Larian.
Sadly it is probably the card itself that is in error, as the in-game book that describes how to make a crossbow also indicates the crafter should use iron and not steel. So, the in-game recipe matches the in-game recipe book, even if neither match the physical card shown above.
It's possible the recipe was intentionally changed as part of a sanity/balance pass on crafting after the cards were sent off for manufacturing. Like the manual they will eventually become largely obsolete as more changes are made (if that happens).