I do know they still technically sing during thunderstorms, but in the mod the loop still plays at full volume, even though realistically most would be hiding from the bad weather, and those that do still stay out would be muffled by the rain.

AmbientSounds plays all other sounds quieter while having rain/ thunder. It's always helpful to provide a screenshot with /ambient-debug turned on, so I can see what is going wrong here. But unfortunately I have dropped support for 1.12, so I won't fix it for that version.

Ah ok. Thanks anyways.