Oh, that's easy to understand. Lumber is used for a lot of consumables (arrows) and uselesses (furniture), whereas leather, ingots and sheets are used for armor, weapons and accessories. Noone (including devs) care about woodworking (high-level bolts and arrows are low skill, compared to high-level weapons and armor, for instance), but blacksmithing, goldsmithing and leatherworking must be pampered with high-demand high-skill low-supply recipes.
Boltmaker doesn't HQ, because it isn't intended to be used by veteran woodworkers but 60 cap woodworkers.
Not that any of that makes much sense to players, but that's dev logic for you.