The bug

Concrete powder only turns into concrete when falling in lava source block. This is inconsistent with water where it turns into concrete when:

• touching water
• falling in any level of water

Code analysis

The method BlockConcretePowder.onEndFalling(world, pos, state, state) tests if the block is a liquid and turns the powder into concrete. The method BlockConcretePowder.func_192425_e(world, pos, state) only tests if the block is water.