Effectively, yesthe idea behind spiraling is you upgrade your hammer, anvil, and finery forge each time you get a 20% crit on the metal. This ensures a slow but gradual increase in your metal quality.
With the changes this world,I do believe you want deep artifice, as that now only changes the chance for bloom to occur, and does not effect the chance of iron/wrought being made from said bloom. If I remember correctly is is 50/50 to become bloom or slag. Then there's various chances for how that bloom turns out.