Hey everyone, here's some news from Anet:
I wanted to give you all a heads up about an upcoming change. We discovered a bug in the crafting recipes for the new legendary weapons Eureka and Shooshadoo. One of them used a Visionary Crystal and one used a Legendary Inscription to craft the third tier precursor. Neither was wrong but it was actually intended that both items be used in the crafting process.
To resolve this, when the next legendary weapon is released, it and all weapons going forward will use a new item, the Visionary Inscription, in their third tier precursors. The Visionary Inscription is crafted from a Visionary Crystal and a Legendary Inscription. In addition, we will adjust the recipe for Eureka’s and Shooshadoo’s third tier precursors to use this new item in order to maintain consistency between all of the recipes.
If you are working on Eureka or Shooshadoo now, you will have until the next weapon is released to craft it using the current recipe.
There is no information on when the next weapon will be released, nor any clues as to what it will be.
Link to forum announcement.