Summary:
Taking damage from lava in a cauldron while it's raining does not play the unique fire damage sound, but instead plays the default sound.

Steps to reproduce:

1. Place the cauldron.
2. Take lava.
3. Pour the lava into the cauldron.
4. Wait or make it rain.
5. Go to survival.
6. Go inside the cauldron.

Observed results:
When taking damage, just the sound of the damage is played.

Expected results:
The sound of fire damage will be played when taking damage in a cauldron of lava.