I know that desynthesis is currently pointless in the game as it's level means absolutely nothing. It's probably calculated something like random()*100+round(skill/100)

That being said, the balance is horrid :
-Goldsmith is the easiest by far as you can get that with most accessories. You can easily cap that just from random dungeons drops
-Weaver/Armorer/Leatherwork are probably the standard balance as it's kinda split evenly between armors.
-Blacksmith is in the same range of the previous group ad it can use most weapons/tools, but require more currencies where the others can be obtained freely.
-Carpenter becomes more difficult, only a few weapons/tools and furnishing. Some DoL accessories used to comes like that, but it's not reliable.
-Alchemist become a lot harder ; only books and a few furnishing.
-Culinarian is probably the hardest. It starts as the easiest on expac release, but after the initial cap you only have big fish. no recipe/furnishing.

So maybe change accessories to be distributed across Goldsmith/Carpenter/Alchemist and introduce desyntable fishes.
Another option would be to merge it with Aetherial reduction for skillup and maybe effect.