As you said the workshops are fully occupied with event crafts.. the Tinker Camp 'should' offer the options needed to complete the spellbound upgrading, as these are a permenant part of the game. New buildings' levels were introduced but the Tinker Camp remains quite simple with it's basic options compared to the busy workshops.
The few spellbound materials crafted inbetween events are consumed by the greedy Elvens, so upgradings remain at a .full stop.