private class SculkVeinGrowChecker extends LichenGrowChecker {

Because the Class that handles this is private, there's no way to access the "canGrow" method.
A simpler solution would be to replace the blockState checks in canGrow with a check to see if the block is in a tag.
This is quite important for mods that want to add new Sculk blocks, so this addition would be much appreciated.