I’m not sure whether this is a bug or intended.
Armourer trophys give jewelcrafting boosts, since there are no separate jewelcrafting trophys.
The Lifestyle projects (town board related) should therefore also give +5 gearscore for crafted jewellery when you have the Inspire Armorers project running. IF not that, add a separate jewelcrafting project. At the moment, Jewelcrafting is therefore the only profession not having the buff available.