The issue

Sculk veins only have a single block state, multi_face_direction_bits, which is basically a glorified damage value, merging all of the properties of the block into a single value which pretty much defeats the purpose of block states. Consequences of this include:

• It's unnecessarily difficult to place a sculk vein in the configuration you want with commands
• It's impossible to detect a sculk vein in a specific direction, since you have to specify the entire bit field
• Java disparity

Java does this with six different true/false block states, one for each direction.

How to reproduce

/setblock ~ ~ ~ sculk_vein["north"=true,"east"=true]
→  Error
Expected result
Sculk vein is placed with sides on the north and east faces of the block.

Notes:

Relates to MCPE-123175.