I'm not sure if it's normal, but it rains in xernic shrubland, while it's supposed to be an hot and arid biome where it doesn't rain like deserts, mesas and savanas.

I guess that would make sense. I disabled rain in the Brushland, Outback, and Oasis as well

You should maybe put them as desert kind biome if it's not already made. I think to that since DynamicSurroundings interacts with the desert kind biomes for adding the sandy tempest effect when it rains.

All biomes are registered properly in the biome dictionary. I'm not sure how Dynamic Surroundings checks for desert/savanna biomes, so if it doesn't work currently, it's something they need to fix.