So I was testing this in 1.16.3 singleplayer to see if it still worked, version 1.2.3. It seems to work for the most part. But I noticed a weird happening where in a new world, a crimson moon would trigger the very first night, then afterwards on different days first thing in the morning, it suddenly makes a message that a crimson moon event is starting, then is immediately followed by a message saying it ended. It's very odd and it did it 2 mornings in a row. Moon chance set to 20.

I'd also like to suggest a feature from the other bloodmoon mods. A setting to use the moon's cycle instead of it being random. So for example, we could have it enable only on full moons, or maybe every other full moon, or only when the moon is nearly gone, etc. Or even chance based on specific cycles; so say a night is a full moon, you could have a 50% chance that it'll be a crimson moon. It ends up pretty cool immersion wise.