Testing 1436 synthesis

[Peka]

I did spiritbond an astral birch ring and conversion resulted in a grade IV craftsmans cunning materia.
Like you i found that crafting increased spiritbonding extremely slowly, and only level 60 one and two star recipes seemed to increase it at all.
However the ring is usable by combat classes, and I found that with two melds on the ring, a complete run of Neverreap increased SB by 14% and Fractal continuum by 20%